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Oculoplastic Surgery
The Essentials

William P. Chen, M.D., F.A.C.S.

Associate Clinical Professor
Department of Ophthalmology
UCLA School of Medicine
Los Angeles, CA;
Senior Attending Surgeon
Ophthalmic Plastic Surgery Service
Department of Ophthalmology
Harbor-UCLA Medical Center
Torrance, CA;
Associate Clinical Professor
Department of Ophthalmology
University of California
Irvine College of Medicine
Irvine, CA

2001
Thieme
New York • Stuttgart


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Thieme New York
333 Seventh Avenue

New York, NY 10001
Editor: Esther Gumpert
Editorial Assistant: Owen Zurhellen
Developmental Editor: Felicity Edge
Director, Production & Manufacturing: Anne Vinnicombe
Marketing Director: Phyllis Gold
Sales Manager: Ross Lumpkin
Chief Financial Officer: Peter van Woerden
President: Brian D. Scanlan
Cover Designer: Kevin Kall
Compositor: Emilcomp Prepare, Inc.
Printer: Canale
Library of Congress Cataloging-in-Publication Data
Chen, William Pai-Dei
Oculoplastic surgery : the essentials / William P. Chen.
p. ; cm.
Includes bibliographical references and index.
ISBN 1-58890-027-4 (hardcover : alk. paper)
1. Ophthalmic plastic surgery. I. Title.
[DNLM: 1. Ophthalmologic Surgical Procedures. 2. Eyelids--surgery. 3. Surgery,
Plastic. WW 168 C518o 2001]
RE87 .C466 2001
617.7'1--dc21
2001027297

Copyright © 2001 by Thieme Medical Publishers, Inc. This book, including all parts thereof, is legally protected
by copyright. Any use, exploitation or commercialization outside the narrow limits set by copyright legislation, without the publisher’s consent, is illegal and liable to prosecution. This applies in particular to photostat
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Important note: Medical knowledge is ever-changing. As new research and clinical experience broaden our

knowledge, changes in treatment and drug therapy may be required. The authors and editors of the material
herein have consulted sources believed to be reliable in their efforts to provide information that is complete
and in accord with the standards accepted at the time of publication. However, in view of the possibility of
human error by the authors, editors, or publisher of the work herein, or changes in medical knowledge, neither
the authors, editors, publisher, nor any other party who has been involved in the preparation of this work,
warrants that the information contained herein is in every respect accurate or complete, and they are not
responsible for any errors or omissions or for the results obtained from use of such information. Readers are
encouraged to confirm the information contained herein with other sources. For example, readers are advised
to check the product information sheet included in the package of each drug they plan to administer to be
certain that the information contained in this publication is accurate and that changes have not been made in the
recommended dose or in the contraindications for administration. This recommendation is of particular
importance in connection with new or infrequently used drugs.
Some of the product names, patents, and registered designs referred to in this book are in fact registered trademarks or proprietary names even though specific reference to this fact is not always made in the text. Therefore,
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publisher that it is in the public domain.
Printed in the United States of America
5 4 3 2 1
TNY ISBN 1-58890-027-4
GTV ISBN 3-13-127451-4


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Contents

CONTRIBUTORS

vii

PREFACE

x

1.

Ophthalmic Facial Anatomy, Don O. Kikkawa and Sunil N. Vasani ………………………………………

1

2.

Fundamentals of Oculoplastic Surgery, Dipak N. Parmar and Geoffrey E. Rose …………………………

21

3.

Entropion, Jan W. Kronish ……………………………………………………………………………………

41

4.

Ectropion, David T. Tse and Ann G. Neff ……………………………………………………………………

55

5.

Trichiasis, Jeffrey A. Nerad and Annie Chang …………………………………………………………………

67

6.

Ptosis Management: A Practical Approach, Steven Dresner ………………………………………………

75

7.

Ptosis: Levator Muscle Surgery and Frontalis Suspension, Philip L. Custer ……………………………

89

8.

Facial Nerve Paralysis, Steven Dresner ……………………………………………………………………… 101

9.

Essential Blepharospasm, John McCann, Stanley Saulny, Robert A. Goldberg, and Richard L. Anderson

10.

Upper Blepharoplasty and Eyebrow Surgery, Clinton D. McCord ……………………………………… 125

11.

Lower Blepharoplasty and Midface Descent, Norman Shorr and Julian D. Perry ……………………… 147

12.

Laser Blepharoplasty, Jemshed A. Khan……………………………………………………………………… 165

13.

Laser Skin Resurfacing, Jemshed A. Khan …………………………………………………………………… 179

14.

Laser Facial Resurfacing: Dual Mode, Cary E. Feibleman ………………………………………………… 195

15.

Asian Blepharoplasty, William Chen ………………………………………………………………………… 211

16.

Periocular Skin Lesions and Common Eyelid Tumors, Gloria M. Bertucci ……………………………… 225

17.

Full-Thickness Eyelid Reconstruction, Ralph E. Wesley, Kimberly A. Klippenstein, Samuel A. Gallo, and
Brian S. Biesman …………………………………………………………………………………………… 243

18.

Lacrimal System, Marc J. Hirschbein and George O. Stasior………………………………………………… 263

19.

Thyroid Ophthalmopathy: Eyelid Retraction, J. Justin Older …………………………………………… 289

20.

Thyroid Opthalmopathy: Restrictive Myopathy, Sherwin J. Isenberg …………………………………… 297

21.

Thyroid Ophthalmopathy: Compressive Optic Neuropathy, Clinton D. McCord ……………………… 305

111

v


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vi • CONTENTS
22.

Thyroid Ophthalmopathy: Orbital Decompression for Aesthetic Indications, Mark A. Codner ……… 315

23.

Enucleation, William Chen …………………………………………………………………………………… 327

24.

Evisceration, William Chen …………………………………………………………………………………… 347

25.

Exenteration, William Chen…………………………………………………………………………………… 355

26.

Anophthalmic Socket, Richard A. Burgett and William R. Nunery ………………………………………… 369

27.

Orbital Diseases, Joseph A. Mauriello Jr. …………………………………………………………………… 387

28.

Orbital Surgery, John Shore…………………………………………………………………………………… 419

29.

Craniofacial and Neurosurgical Approaches to the Orbit, M. Douglas Gossman, Dale M. Roberts,
and George Raque …………………………………………………………………………………………… 451

30.

Management of Orbital Injuries, Stuart R. Seiff …………………………………………………………… 475

Index ………………………………………………………………………………………………………………… 490


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Page vii

Contributors
Richard L. Anderson M.D.
Salt Lake City, UT
Gloria M. Bertucci, M.D.
Associate Pathologist
Department of Pathology
Long Beach Memorial Medical Center
Long Beach, CA
Brian S. Biesman, M.D.
Director of Laser Research
Center for Eyelid and Aesthetic Surgery

Nashville, TN
Richard A. Burgett, M.D.
Assistant Professor
Department of Ophthalmology
Indiana University
Indianapolis, IN
Annie Chang, M.D.
Eye Surgery Center of Colorado
North Denver, CO
Mark A. Codner, M.D.
Clinical Assistant Professor
Department of Plastic Surgery
Emory University
Atlanta, GA
Philip L. Custer, M.D.
Professor
Department of Ophthalmology and Visual Sciences
Washington University School of Medicine
St. Louis, MO
Steven Dresner, M.D.
Assistant Clinical Professor
Doheny Eye Institute
University of Southern California
Los Angeles, CA
Cary E. Feibleman, M.D.
Assistant Clinical Professor of Dermatology, Emeritus
Department of Medicine
Division of Dermatology
University of California at Los Angeles Medical School
Long Beach, CA

Samuel A. Gallo, M.D.
Department of Ophthalmology
University of Tennessee Health Sciences Center
Memphis, TN
Robert A. Goldberg, M.D.
Associate Professor of Ophthalmology
Department of Ophthalmology
Jules Stein Eye Institute
University of California
Los Angeles, CA
M. Douglas Gossman, M.D.
Associate Professor
Department of Ophthalmology and Visual Sciences
University of Louisville
Louisville, KY
Marc J. Hirschbein, M.D.
Clinical Instructor
Wilmer Eye Institute
Department of Ophthalmology
The John Hopkins University
Sinai Hospital of Baltimore
Baltimore, MD
Sherwin J. Isenberg, M.D.
Professor of Ophthalmology and Pediatrics
Vice Chairman
Department of Ophthalmology
Jules Stein Eye Institute
University of California
Los Angeles, CA

Jemshed A. Khan, M.D.
Clinical Professor
Department of Ophthalmology
Kansas University School of Medicine
Kansas City, KS
Don O. Kikkawa, M.D.
Associate Professor
Department of Ophthalmology
UCSD School of Medicine
La Jolla, CA

vii


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viii • CONTRIBUTORS
Kimberly A. Klippenstein, M.D.
Assistant Clinical Professor of Ophthalmology
Vanderbilt Medical Center
Nashville, TN
Jan W. Kronish, M.D.
Clinical Associate Professor
Department of Ophthalmology

Bascom Palmer Eye Institute
University of Miami School of Medicine
Delray Eye Associates
Delray Beach, FL
Joseph A. Mauriello, Jr., M.D.
Clinical Associate Professor
Department of Ophthalmology
University of Medicine and Dentistry—New Jersey
Medical School
Summit, NJ
John McCann, M.D., Ph.D.
Assistant Professor
Department of Ophthalmology
Jules Stein Eye Institute
University of California
Los Angeles, CA
Clinton D. McCord, M.S., M.D.
Paces Plastic Surgery
Atlanta, GA
Ann G. Neff, M.D.
Assistant Professor
Department of Ophthalmology
University of Miami
Bascom Palmer Eye Institute
Miami, FL
Jeffrey A. Nerad, M.D.
Professor
Department of Ophthalmology
University of Iowa
Iowa City, IA

William R. Nunery, M.D.
Clinical Associate Professor
Department of Ophthalmology
Indiana University,
Midwest Eye Institute
Indianapolis, IN
J. Justin Older, M.D.
Clinical Professor
Department of Ophthalmology
University of South Florida College of Medicine
Tampa, FL

Dipak N. Parmar, B.Sc(Hons.), M.B.B.S.,
F.R.C.Ophth.
Specialist Registrar in Ophthalmology
Adnexal Department
Moorfields Eye Hospital
London, UK
Julian D. Perry, M.D.
Department of Ophthalmic Plastic and Orbital Surgery
Cole Eye Institute
Cleveland Clinic
Cleveland, OH
George Raque, M.D.
Associate Professor and Vice Chair
Department of Neurosurgery
University of Louisville
Louisville, KY
Dale M. Roberts, M.D.
Clinical Associate Professor

Department of Plastic Surgery
University of Louisville
Louisville, KY
Geoffrey E. Rose, M.D., M.R.C.P., F.R.C.Ophth.
Consultant Ophthalmic Surgeon
Orbital and Adnexal Department
Moorfields Eye Hospital
London, UK
Stanley Saulny, M.D.
Resident Physician
Department of Ophthalmology
Jules Stein Eye Institute
University of California
Los Angeles, CA
Stuart R. Seiff, M.D., F.A.C.S.
Professor of Ophthalmology
Director of Ophthalmic Plastic and Reconstructive
Surgery
University of California San Francisco, and
Chief, Department of Ophthalmology
San Francisco General Hospital
San Francisco, CA
John Shore, M.D.
Texas Oculoplastic Consultants
Austin, TX
Norman Shorr, M.D., F.A.C.S.
Clinical Professor of Ophthalmology,
Director, Fellowship in Orbital Facial Plastic Surgery
Jules Stein Eye Institute
University of California at Los Angeles

Los Angeles, CA


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CONTRIBUTORS • ix
George O. Stasior, M.D., F.A.C.S.
Clinical Professor
Department of Ophthalmology
Albany Medical College
Albany, NY

Sunil N. Vasani, M.D.
Clinical Instructor
Department of Ophthalmology
UCSD School of Medicine
La Jolla, CA

David T. Tse, M.D.
Professor
Department of Ophthalmology
University of Miami
Bascom Palmer Eye Institute
Miami, FL

Ralph E. Wesley, M.D.
Clinical Professor of Ophthalmology
Vanderbilt University Medical College
Nashville, TN, and
Clinical Professor of Ophthalmology
University of Tennessee Health Sciences Center
Memphis, TN


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Page x

Preface
When I was approached three years ago regarding the feasibility of a book project on the
essentials of oculoplastic surgery, my thoughts were that there should be a better way to
present the modern concepts of this field in a succinct fashion. There are a few excellent
oculoplastic surgery books on the market, but the majority of them still present the ideas
with a lengthy and often traditional approach. My aim for this book was to solicit the best
group of authors who are excellent clinicians as well as teachers in the academic field,
and ask them to write about a special topic in their field of expertise.
To achieve this ambitious goal, I planned to design and orchestrate the flow of the
content so that it would be highly readable and clinically practical, supplemented with
clear illustrations as well as line drawings. The illustrations would include color images,
black and white photos, digital images, line drawings, and algorithms. We would add

“Pearls”, “Pitfalls”, and “Recommendations” to the text, as well as summaries of clinical
thought processes in the form of decision trees, or “Clinical Pathways”. The bibliography
of each chapter would be relevant and not encyclopedic. All this would make each individual chapter and its content informative and practical; the book would serve as an excellent teaching textbook, as well as provide updates on the most recent concepts of
oculoplastic surgery.
The aim was for our target audience to include comprehensive ophthalmologists
and resident physicians-in-training, as well as subspecialty-trained practitioners interested in a succinct update on the field of oculoplastic surgery. This latter group would
include head-and-neck surgeons, plastic surgeons, neurosurgeons, dermatologists, and
eye-care professionals.
In terms of the breadth of topics covered, traditional texts tend to concentrate on
reconstructive aspects of oculoplastic surgery. Some specialized textbooks concentrate
separately, and perhaps predominantly, on aesthetic surgery, while others concentrate
on orbital diseases and surgery. I have elected to cover fundamental aspects of oculoplastic surgery in a thorough fashion in the first nine chapters of this book, (entropion,
ectropion, trichiasis, ptosis, facial nerve paralysis, and blepharospasm). With the increasing popularity and interest in aesthetic surgery, I have allocated six chapters to upper
and lower blepharoplasty, surgery of the eyebrows, the field of laser eyelid surgery and
facial resurfacing, as well as blepharoplasty methods unique for Asian patients. There is
a rich source of information in these chapters unavailable anywhere in a single text source.
The second half of the book has three chapters that deal with common eyelid lesions,
the entire spectrum of full-thickness eyelid reconstruction, and the important topic of the
lacrimal system and disorders. There are four chapters that deal with the problems associated with thyroid ophthalmopathy, including eyelid retraction, post-inflammatory
restrictive myopathy, and orbital decompression for sight-threatening as well as aesthetic
indications.
The last seven chapters discuss pathology and trauma of the orbit, as well as surgical approaches. They include treatment of the anophthalmic socket and a comprehensive
chapter on orbital diseases, orbital surgery, orbital injuries, and the combined disciplines
of craniofacial and neurosurgical approaches to the orbit. The three chapters on enucleation, evisceration, and exenteration provide the most up-to-date information on reconstructive techniques and presently available implant materials, as well as information on
comparative costs and motility results. In essence, the book provides a concentrated

x


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PREFACE • xi
collection of information available from the three major fields of general oculoplastic
surgery, aesthetic oculoplastic surgery, and orbital diseases and surgery.
I am very pleased to say that we have achieved our goals for this project, drawing on
the expertise of 38 distinguished colleagues in the fields of oculoplastic surgery, orbital
surgery, plastic surgery, and other disciplines including neurosurgery, dermatology, and
pathology. Many of the authors are members of the American Society of Ophthalmic
Plastic and Reconstructive Surgery, most of whom are actively engaged in university
teaching programs, with nine of the contributors serving as Fellowship Preceptors
(Mentors) for accredited fellowship programs of the American Society of Ophthalmic
Plastic and Reconstructive Surgery.
I thank all of the contributing authors for making this project possible. I would not
have been able to complete this project without the help of every one of them, and for this
I am most grateful. On the personal side, I thank my wife Lydia, my children Katherine
and Andrew, and my mother Katie for being supportive and tolerant of my efforts.
Equally important, I thank the highly professional staff at Thieme Medical Publishers for making this project possible: Andrea Seils for kindling my interest in the project;
Brian Scanlan (President, New York) for supervising the project; Owen Zurhellen,
Michelle Carini, and Thomas Soper (Editorial Assistants) for their tireless efforts and helpful suggestions; Esther Gumpert (Consulting Medical Editor) for helping me stay centered; and Anne Vinnicombe (Director of Production and Manufacturing), Felicity Edge
(Development Editor), and Chris Gauss for their editorial skills, as well as keeping me
informed at all stages. I am grateful to Linda Warren, Director of Medical Illustrations
and Audiovisual Education at Baylor College of Medicine in Houston, Texas, for her artistic talents and uncompromising punctuality in completing the often-arduous assignments
I gave her. Lastly, I thank the library staff, including Emi Wong, at the Long Beach Memorial Medical Center of Long Beach, California, for their assistance in all my article
retrievals and research needs over the period I worked on this project.

William P. Chen, M.D., F.A.C.S.


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I wish to express my gratitude to Dr. Sonny McCord for teaching me oculoplastic surgery.


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Chapter 1

OPHTHALMIC FACIAL ANATOMY
Don O. Kikkawa and Sunil N. Vasani

The expanding realm of the plastic and reconstructive
ophthalmic facial surgeon demands an intimate
understanding of eyelid, lacrimal, orbital, and facial

anatomy. With improvements in technique and instrumentation, traditional surgical boundaries are now
being surpassed. Hence, as always, the surgeon of the
21st century must have a strong foundation in clinical
and surgical anatomy to perform successful surgery.

OPHTHALMIC FACIAL SURFACE
ANATOMY
Facial Dimensions
The face has ideal aesthetic proportions. Artists have
long recognized the visually pleasing ratios of the specific vertical and horizontal facial dimensions. The
ideal facial dimensions are five eye widths wide and
eight eye widths high.1 The ideal face also has a
slightly oval shape.
Overall facial dimensions and proportions are critical in aesthetic and reconstructive surgery. The eyes
and corresponding areas of the upper and midface
represent key aesthetic units that must be visualized
in the context of overall facial features.

Topography and Cutaneous Landmarks
The eyebrows are a foundation for the eyelids. They
typically arch above the supraorbital rim and their
lower border should lie 1 cm above the lateral portion
of the orbital rim, with its highest point directly above
the lateral limbus.2 Eyebrow cilia are directed at different angles in the upper and lower eyebrow. In the
upper eyebrow, the cilia are directed downward from

the vertical plane and in the lower eyebrow, they are
directed upward from the vertical plane.3 Medially,
all cilia are directed superiorly. Brow incisions should
be planned accordingly to preserve cilia. With aging,

repeated frontalis muscle contraction creates deep
horizontal furrows in the forehead. Vertical glabellar
furrows, medial to the eyebrow, result from repeated
corrugator muscle contraction, while horizontal
glabellar furrows result from the procerus.
The adult palpebral fissures measure 9 to 11 mm
vertically and 28 to 30 mm horizontally. Ideally, the
two medial canthi are separated by one horizontal
palpebral width. The upper eyelid is positioned at the
upper limbus and may cover 1 to 2 mm of the cornea.
The highest point of the upper lid margin is just nasal
to the central pupillary axis (Fig. 1–1). The upper eyelid crease is formed by the terminal interdigitations of
the levator aponeurosis along the superior tarsal border.4 Typically, the eyelid crease measures 10 to 12 mm
in women and 7 to 8 mm in men. Asians have a low or
ill-defined eyelid crease because of the low insertion
of the orbital septum on the levator aponeurosis.5
The lower eyelid normally rests at the inferior limbus and its lowest point is just lateral to the pupil. The
lower eyelid crease is formed from cutaneous insertions of the lower eyelid retractors. The retractors consists of the capsulopalpebral fascia and the inferior
tarsal muscle. It begins medially 4 to 5 mm below the
eyelid margin and slopes inferiorly as it continues laterally. The malar and nasojugal folds represent the
cutaneous insertion of the orbitomalar ligament.6 Horizontal skin folds (laugh lines) that emanate from the
lateral canthal angle result from skin folding due to
orbicularis oculi. With aging as well as thinning of

1


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2 • OCULOPLASTIC SURGERY: THE ESSENTIALS
Supratarsal
sulcus

Superior
lid crease

Punctum
Superior eyelid
skinfold

Lateral
commissure

Medial
commissure

Inferior
lid crease
Punctum
Nasojugal
fold

Malar fold

Nasolabial fold

FIGURE 1–1 Normal eyelid topography.

dermis, these laugh lines become static and rhytids
develop (“crow’s feet”). The lateral canthal angle is
normally 2 mm higher than the medial canthal angle,
giving the eyelids a slight upward flare.
Surface marking of the nasolacrimal duct is seen by a
line joining the medial canthal angle of the eye to the
canine tooth (eye tooth) on the same side. The upper and
lower puncta are located in each eyelid 5 to 7 mm lateral to the medial canthal angle. The lower puncta is
usually located 1 to 2 mm lateral to the upper punctum.

The Eyebrow
The eyebrows form a key landmark of the upper
facial continuum. The skin of the eyebrows represents
a transition zone between the thinner skin of the eyelids and the thicker skin of the forehead and scalp.
Evaluation of eyebrow position is critical in the planning of surgery of the eyelids.
The position of the eyebrows represents a dynamic
interplay between elevating and depressing forces. The
two forces are the elevators (frontalis) and the depressors (orbicularis oculi, corrugator, and procerus). A
submuscular fat pad exists under the interdigitation of
the frontalis and orbicularis muscles.7 Termed the eyebrow fat pad or retroorbicularis oculi fat pad (ROOF),
it continues into the eyelid as the posterior orbicularis

fascia.8, 9 Eyebrow fat can be mistakenly identified as
orbital fat and can be debulked in certain patients with
prominent eyebrow bulk. Submuscular fat in the eyebrow region (ROOF) is continuous with suborbicularis
oculi fat (SOOF) of the lower lid.

P

...

EARL
The surgeon dissecting in
region of the eyebrow fat must pay careful
attention to the presence of the supraorbital
nerve and vessels.10
The Eyelids
Eyelid skin is among the thinnest of the body and is
useful for hiding cutaneous incisions. Eyelid skin
is nearly devoid of subcutaneous fat. Eyelid development occurs through a complex inductive interaction
between mesoderm and ectoderm (Fig. 1–2). Eyelid
anomalies occur secondary to arrests in various stages
of this process.
One of the key surgical landmarks of the eyelids is
the orbital septum. The orbital septum defines the
anterior extent of the orbit and the posterior extent of
the eyelids. It arises from the arcus marginalis, a white
fibrous line that arises circumferentially along the


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OPHTHALMIC FACIAL ANATOMY • 3
Complex Inductive Interaction
of Eyelid Development

Mesoderm

Frontonasal
process

Non-fusion

Colobomas

Ectoderm

Maxillary
process

Skin

Conjunctiva

Fusion
Between
[medial and
lateral processes]

Upper

eyelids

Lower
eyelids

Separation
at 5 months

Failure or
incomplete separation

Normal
eyelids

Ankyloblepharon

FIGURE 1–2 Eyelid development.

periosteum of the bony orbital margin. In the upper
lid, the orbital septum fuses with the levator aponeurosis11 at or up to 10 mm from the superior tarsal border, and in the lower eyelid it fuses with the lower
eyelid retractors just inferior to the tarsus. The orbitomalar ligament emanates from the arcus marginalis
of the inferior orbital rim, traversing through the
orbicularis oculi to insert into the dermis of the lower
lid. 12 This cutaneous insertion corresponds to the
malar and nasojugal skinfolds. With aging, the orbitomalar ligament elongates and the orbital septum
attenuates, allowing orbital fat to move anterior and
sometimes herniate below the inferior orbital rim.

EARL... Surgically, the orbital sep-

P

tum may be identified by a traction test
to feel its firm attachments to the orbital rim.
The backbone of each eyelid, the tarsus, is composed
of dense fibrous tissue and houses the meibomian
glands. The tarsus measures 10 to 12 mm vertically in
the upper lid and close to 4 mm in the lower eyelid.13
Conjunctiva firmly lines the inner aspect of the tarsal

plates and reflects onto the bulbar surface of the globe.
The medial and lateral canthal ligaments anchor
the eyelids horizontally to the orbital rims. The medial
canthal ligament inserts on both the anterior and posterior lacrimal crests.14 The medial canthal ligament is
associated with Horner’s muscle (the deep head of the
pretarsal and preseptal orbicularis muscle) with both
of them inserting on the posterior lacrimal crest.
Lacrimal excretory pump function is dependent on
the contraction of Horner’s muscle, which draws the
eyelids medially and posteriorly. The lateral canthal
ligament inserts on Whitnall’s tubercle.
The tarsoligamentous band normally provides the
horizontal tension to keep the eyelids opposed to the
globe. Horizontal laxity that occurs with aging leads
to eyelid malposition. With globe protrusion from
exophthalmos a compensatory lengthening may
occur, reducing eyelid retraction.15
The main eyelid protractor is the orbicularis oculi
muscle. It forms part of the superficial musculoaponeurotic system (SMAS). The orbicularis oculi is
divided into three parts: pretarsal, preseptal, and

orbital.16 The muscle of Riolan is a small portion of the
pretarsal orbicularis that corresponds anatomically to
the gray line.17


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4 • OCULOPLASTIC SURGERY: THE ESSENTIALS

Superficial galea
Deep galea
Anterior and posterior
deep galea
Sub-brow fat pad (ROOF)
Frontalis muscle
Preaponeurotic fat
Orbital septum
Preseptal fat (ROOF)
Orbicularis oculi muscle
Müller’s muscle
Levator aponeurosis
Superior tarsus
Conjunctiva

Inferior tarsus
Inferior tarsal muscle
Capsulopalpebral
fascia (CPF)
Orbital septum
Orbital fat
Inferior oblique
muscle

FIGURE 1–3 Eyebrow and eyelid
anatomy (cross section).

The levator palpebrae superioris (Fig. 1–3) is one
of the retractors of the upper eyelid. It is tendinous in
its distal 14 to 20 mm and the transition from muscular to aponeurotic portions occurs at Whitnall’s ligament. The aponeurosis inserts onto the anterior tarsal
surface via an elastic fiber attachment,18 and interdigitates into the orbicularis muscle fibers and dermis,
creating the upper eyelid crease. Medially and laterally the horns of the levator anchor to periosteum
with the lateral horn of the levator dividing the
lacrimal gland into orbital and palpebral lobes.
With advancing age, the levator rarefies and may
disinsert from the tarsal attachments leading to ptosis.19

EARL ... Medial dehiscence of the

P

levator can lead to horizontal instability
that may create difficulty in adequately elevating the upper eyelid during ptosis surgery.
Another manifestation is the lateral shifting of
the tarsal plate.

Orbicularis muscle
Malar fat pad
Suborbicularis oculi
fat (SOOF)

Müller’s muscle arises from beneath the levator
palpebrae superioris, 15 mm from the upper tarsal
border. It consists of smooth muscle and is firmly
adherent to the conjunctiva. Müller’s muscle is innervated by the sympathetic nervous system and inserts
on the superior tarsal border. It provides the upper
lid an additional 2 mm of lift. Recent studies have
shown that Müller’s muscle extends laterally between
the orbital and palpebral lobes of the lacrimal gland
along with the lateral horn of the levator. Hence it
may accentuate the lateral flare of the palpebral fissure frequently seen in eyelid retraction associated
with thyroid eye disease.21
The lower eyelid retractors depress the lower eyelid in downgaze. They consist of the capsulopalpebral
fascia and the inferior tarsal muscle.20 The capsulopalpebral fascia arises from the inferior rectus and
inferior oblique muscles. The inferior tarsal muscle
consists of smooth muscle. The lower eyelid retractors are commonly incised during the transconjunctival surgical approach, but this leads to a relatively
low incidence of postoperative eyelid malposition
(Fig. 1–4).


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OPHTHALMIC FACIAL ANATOMY • 5
The Midface

FIGURE 1–4 Clinical photo of transconjunctival dissection
of lower eyelid. Note forceps pointing to lower lid retractors.

PITFALL
Disinsertion of the lower lid retractors leads to
vertical lower lid instability and is part of the
pathophysiology of both involutional ectropion
and entropion. Clinically, this may be seen by
decreased excursion of the lower lid and a
white horizontal line in the inferior fornix.

The midface extends from an imaginary line between
the medial and lateral canthi to the mouth. Medially,
the maxilla and laterally the zygoma form most of the
bony skeleton of the midface. Prominent bony landmarks include the infraorbital foramen, which lies
several millimeters inferior to the inferior orbital rim,
and, laterally, the zygomaticofacial foramen.
The muscles of the face that contribute to facial
expressions are called the mimetic muscles (Fig. 1–5).
Most of these muscles originate from the midfacial
region. The levator labii superioris alacque nasi muscle originates on the frontal part of the maxilla and
inserts on the alar cartilage and the upper lip. It
dilates the nostril, raises the upper lip, and deepens
the nasolabial fold. The levator labii superioris muscle

arises just superior to the infraorbital foramen and
overlies the infraorbital vessels and nerve to insert in
the upper lip. Its main action is to raise the upper lip.
The levator anguli oris muscle arises inferior to the
infraorbital foramen and inserts into the angle of
the mouth. It causes the expression of contempt and
deepens the nasolabial fold. The zygomaticus major
and minor clinically appear as one complex. They
arise from the zygoma close to the zygomaticomaxillary suture and draw the mouth upward and outward, for example in smiling.

Frontalis muscle

Supraorbital
artery and nerve

Temporal branch
of facial nerve

Supratrochlear
nerve
Orbicularis oculi muscle

Zygomatic branches
of facial nerve
Buccal branches
of facial nerve

Infraorbital nerve
Levator labii superioris
Zygomaticus minor muscle

Zygomaticus major muscle

Mandibular branch
of facial nerve
Cervical branch
of facial nerve

FIGURE 1–5 Muscles of facial expression and branches of facial nerve.


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6 • OCULOPLASTIC SURGERY: THE ESSENTIALS

SMAS AND SOOF
Mitz and Peyronie described the SMAS, a distinct fibromuscular layer that spreads out in a fan-like fashion over
the face. The SMAS functions to transmit and distribute
the facial muscle contractions to the skin. The orbicularis
oculi muscle is part of the SMAS and has a distinct bony
attachment, the orbitomalar ligament.6 With aging, the
midfacial soft tissues become ptotic, resulting in the typical biconvex topographic appearance.23
Fat located deep to the orbicularis oculi and anterior to the periosteum in the midface has been termed
the SOOF.22 Its descent contributes to the formation of
“malar bags.” The SOOF varies in thickness from

medial to lateral, being most prominent in the central
and lateral positions. In the midface it engulfs the
mimetic muscles and lies superficial to the periosteum.

EARL... With proper dissection in

P

the SOOF plane, either subperiosteal or
preperiosteal, the entire midface can be elevated and mobilized22, 24 (Fig. 1–6).

NERVES, LYMPHATICS,
AND VASCULATURE
Both internal and external carotid arteries supply the
eyelids and midface. The external carotid artery contributes the facial artery, the superficial temporal
artery, and the infraorbital artery. The facial artery
courses from below the mandible and runs superiorly
and medially; it terminates as the angular artery in the
medial canthal region. The angular artery lies 6 to
8 mm medial to the medial canthus and 5 mm anterior
to the lacrimal sac. Lacrimal and anterior orbitotomy
incisions should be planned accordingly to avoid this

artery. The superficial temporal artery lies superficial
to the muscle plane of the temporalis muscle.
The internal carotid artery contributes to the eyelid
blood supply by the terminal branches of the ophthalmic, lacrimal, frontal, supraorbital, and nasal
arteries. The marginal and peripheral arcades of the
upper eyelid are formed by anastomosis between
the lacrimal and nasal arteries. The marginal arcade

is located 2 to 3 mm from the upper eyelid margin,
and the peripheral arcade lies along the upper tarsal
border near its attachment to Müller’s muscle. Eyelid
reconstruction with tarsoconjunctival pedicles and
tarsal fracture techniques should avoid interruption
of the arcades if possible. The dual arcade in the lower
eyelid is much less developed.

P

...

EARL
The location of the superficial temporal artery in the subcutaneous
plane makes this a good landmark during temporal artery biopsy.
The orbital and facial veins also anastomose in the
eyelids and midface. The angular, superior ophthalmic and supraorbital veins all communicate
superomedially in the orbit and hence can propagate
facial infection into the cavernous sinus.
Medially, lymphatic drainage from the eyelids and
conjunctiva drains into the submandibular nodes
and laterally into the preauricular nodes.
The eyelids are innervated by the facial nerve (cranial nerve VII), the oculomotor nerve (cranial nerve
III), the trigeminal nerve (cranial nerve V), and sympathetic nerves from the superior cervical ganglion.
Motor innervation of the levator palpebrae superioris
and Müller’s muscle, as well as sensory innervation of
the eyelids are discussed in the orbital section, below.
After exiting the stylomastoid foramen, the facial
nerve passes through the parotid gland and divides
into the following divisions: temporal, zygomatic,

buccal, mandibular, and cervical. The frontal branch
arises from the temporal division and travels within
the temporoparietal fascia (superficial temporal fascia) to innervate the frontalis muscle.

PITFALL

FIGURE 1–6 Clinical photo of suborbicularis oculi fat
(SOOF) in left lower lid. Suture being passed through SOOF
prior to advancement to orbital rim.

The frontal branch is one of the most commonly injured nerves in surgical dissections of
the temporal region, particularly during forehead lifting procedures. Any dissection should
be accomplished beneath the plane of the temporoparietal fascia to avoid injury to the nerve.


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OPHTHALMIC FACIAL ANATOMY • 7
The orbicularis oculi is innervated by temporal,
zygomatic, and buccal divisions with extensive overlap between them. The remainder of the facial
mimetic muscles are innervated by the zygomatic and
buccal divisions.

ORBIT

P

...

EARL
Safe subperiosteal dissection may be accomplished along the lateral wall and orbital floor for 25 mm and along
the medial wall and orbital roof for 30 mm.26
Orbital Margins (Fig. 1–7)

Orbital Shape and Dimensions
The shape of the bony orbit approximates a foursided pyramid, which becomes three sided more posteriorly, due to the absence of the orbital floor
posteriorly.25 In the adult, the medial walls of the orbit
are 25 mm apart and are parallel until they converge
near the orbital apex. The anterior end of the medial
wall lies 20 mm in front of the lateral wall. The
entrance to the orbit is rectangular, measuring 40 mm
horizontally by 32 mm vertically. In adults, the depth
from orbital rim to apex varies from 40 to 45 mm.
Orbital volume is roughly 30 cc, but varies with race
and sex.

The orbital margin is an incomplete circle and forms a
quadrilateral spiral due to the presence of the lacrimal
sac fossa medially. The superior orbital rim is formed
in its entirety by the frontal bone. At the junction of the
medial one third with the lateral two thirds of the superior rim is the supraorbital notch (in 75% of the population) or foramen (in 25% of the population). The
medial orbital margin is formed by three bones: the
frontal bone, the posterior lacrimal crest of the lacrimal
bone, and the anterior lacrimal crest of the frontal

process of the maxillary bone. The inferior orbital rim is
derived from the maxillary bone medially and zygomatic bone laterally. The zygomaticomaxillary suture

Orbit

Margins

Walls

Superior

Lateral

Medial

Inferior

Superior

Lateral

Medial

Inferior

Frontal
bone

Superior
1/4th frontal

Frontal
bone

Maxilla
medially

Frontal bone
anteriorly

Zygoma
anterior

Anterior maxilla
and lacrimal

Anterior
maxilla

+

+

Inferior 3/4th
zygomatic

Lacrimal
(posterior
lacrimal crest)

Zygomatic
laterally

Lesser wing
of sphenoid
posteriorly

Greater wing
of sphenoid
posterior

Ethmoid
lamina
papyracea

Antero-lateral
zygoma

Union of
Strongest
medial 1/3 and Facial buttress
lateral 2/3

Maxilla
(ant. lacrimal
crest)

Infra-orbital
foramen
1 cm inferior

to margin

Frontoethmoid
suture

Frontozygomatic
suture

Posterior
body of
sphenoid

Posterior
palatine

Sutura notha
(lateral aspect
of maxilla)

Upper limit
for bony
medial wall
removal

Mark for
superior
incision in lateral
wall removal

Posterior

and anterior
ethmoid
foramen

Inferior
orbital
fissure

Branch of
infra-orbital
artery

Anterior and
posterior
ethmoidal
arteries

Upper limit
medial wall
removal

Limit for
floor
removal

Supra-orbital
notch

+

May bleed
during
dacryocystorhinostomy

FIGURE 1–7 Orbital walls and margins.


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8 • OCULOPLASTIC SURGERY: THE ESSENTIALS
lies at the junction of the medial one third and lateral
two thirds of the inferior orbital rim. The infraorbital
foramen is closer to the orbital margin at birth and
grows further away, being 1 cm from the rim in the
adult. The upper one fourth of the lateral orbital rim is
formed by the zygomatic process of the frontal bone
and the lower three fourths is formed by the frontal
process of the zygomatic bone. Articulation occurs at
the zygomaticofrontal suture, a site where a palpable
step is found in cases of fracture.

P

...

EARL
Along the lateral aspect of
the frontal process of the maxilla, a fine
groove, the sutura notha, can be found.27 This
groove lodges a branch of the infraorbital artery,
and is important when performing external
dacryocystorhinostomy in that bleeding may be
encountered from this site.

...

P

EARL
Blunt trauma to the forehead can cause indirect traumatic optic
neuropathy due to the transmission of force
along the orbital roof to the optic canal.
Medial Orbital Wall
The medial orbital wall is formed by the maxillary,
lacrimal, ethmoid, and sphenoid bones. The main
landmarks of the medial wall are the anterior and
posterior ethmoidal foramina located in a plane just
superior to the medial canthal ligament; they are
20 mm and 35 mm posterior to the anterior lacrimal
crest, respectively. 27 The frontoethmoidal suture
marks the boundary between the roof and the medial
wall and the upper limit for bone removal during
orbital decompression. The optic foramen is located
approximately 50 mm posterior from the anterior

lacrimal crest.

Orbital Walls

PITFALL

Seven bones take part in the formation of the orbit:
the frontal, sphenoid, lacrimal, ethmoid, maxilla,
zygomatic, and palatine (Fig. 1–8). Of these the sphenoid bone is present in three of the orbital walls and
contributes some of the most important structures.

Roof
The orbital roof is formed by the orbital plate of the
frontal bone and the lesser wing of the sphenoid
bone posteriorly. The anterior part of the roof is
3 mm thick anteriorly near the frontal sinus, but it
thins posteriorly.

Cerebrospinal fluid (CSF) leaks can occur
with dissection along the medial wall. The
anterior cranial fossa is located at an average
of 8.3 mm superior to a point 10 mm posterior to the medial canthal tendon.28

Orbital Floor
The orbital floor is formed primarily from the maxilla,
with contributions from the palatine bone posteriorly

Greater sphenoid
wing

Lesser
sphenoid
wing

Frontal bone
Palatine bone

Ethmoid
bone
Zygomatic
bone
Lacrimal
bone
Inferior orbital
fissure
Infraorbital
groove

FIGURE 1–8 Right adult human
orbit (anterior lateral view).

Nasolacrimal
canal
Orbital
plate of
maxillary
bone

Maxilla

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OPHTHALMIC FACIAL ANATOMY • 9
and the zygoma anterolaterally. Along the course of
the orbital floor from posterior to anterior, the
infraorbital nerve becomes intraosseous within
the infraorbital canal and is lined by periorbita.
The thinnest area of the orbital floor occurs posteromedially to the infraorbital nerve. Most blowout
fractures occur here. Dissection along the medial
aspect of the floor can disrupt the origin of the inferior
oblique, located just lateral to the nasolacrimal canal.

PITFALL
The internal maxillary artery lies immediately
behind the posterior wall of the maxillary
sinus. Orbital floor dissection posterior to the
inferior orbital fissure could damage this
major vessel.
Lateral Wall
The lateral orbital wall divides the orbit from the temporalis muscle anteriorly and the middle cranial fossa
posteriorly. It is composed of the zygoma and the
greater wing of the sphenoid. Landmarks of the lateral orbital wall include Whitnall’s lateral orbital
tubercle, and the zygomaticotemporal and zygomaticofacial foramina. The posterior boundary of the lateral orbital wall is the superior and inferior orbital

fissures. Whitnall’s tubercle is located approximately
3 to 4 mm behind the orbital rim and 11 mm inferior
to the frontozygomatic suture.29 It is an insertion site
for the lateral canthal ligament, the deep pretarsal
orbicularis insertion, the lateral horn of the levator
aponeurosis, the check ligament of the lateral rectus
muscle, the superior (Whitnall’s) and inferior (Lockwood’s) transverse ligaments, and an expansion of
the superior rectus muscle sheath.30
During lateral orbitotomy, the zygomaticosphenoid suture is a natural breaking point for removal of
the lateral rim. If further removal of bone is desired,
deeper dissection within the greater wing of sphenoid
will reveal a marrow space and brisk hemorrhage.
The middle cranial fossa has been found to be 12 to
13 mm posterior from the superior osteotomy made in
a lateral orbitotomy.31

P

...

EARL
Deep lateral wall removal
can be safely done during orbital decompression. Dural exposure can occur if the inner
aspect of the greater sphenoidal wing is
removed (Fig. 1–9).

FIGURE 1–9 Clinical photo showing marrow space of
greater wing of sphenoid during orbital decompression.
Lateral orbital rim and wall have been removed.

Orbital Apex (Fig. 1–10)
Three key orbital apex landmarks—the optic foramen,
the superior orbital fissure, and the inferior orbital fissure—communicate with the intracranial cavity,
pterygopalatine fossa, and paranasal sinuses.
The superior orbital fissure lies between the greater
and lesser wings of the sphenoid. The annulus of Zinn
divides the fissure into three parts. The trochlear,
frontal, and lacrimal nerves, the superior ophthalmic
veins, and the recurrent lacrimal artery pass through
the upper part. The superior division of the third
nerve, the nasociliary nerve, the sympathetic root of
the ciliary ganglion, the inferior division of third
nerve, and the abducens nerve are in the middle section. The inferior part has the ophthalmic veins.
The inferior orbital fissure is bounded laterally by
the greater wing of the sphenoid and medially by the
palatine and maxillary bones. The inferior orbital fissure communicates with both the pterygopalatine and
infratemporal fossae. Blood from the temporalis fossa
can reach the orbit through this communication. The
maxillary division of the trigeminal nerve, the infraorbital artery, the inferior orbital vein, and autonomic
branches from the pterygopalatine ganglion pass
through the inferior orbital fissure.

P

...

EARL
The infraorbital artery
gives blood supply to the inferior rectus
and inferior oblique muscles. The surgeon

should be aware of these branches during inferior orbitotomy.32
The optic foramen, located in the lesser wing of the
sphenoid, houses the optic nerve and ophthalmic
artery. The canal reaches adult size by 3 years of age.


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10 • OCULOPLASTIC SURGERY: THE ESSENTIALS
Orbital Apex

Superior orbital
fissure

Inferior orbital
fissure

Optic
foramen

22 mm length

20 mm length

8–10 mm

Between greater and lesser
wings of sphenoid bone

Laterally greater
wing of sphenoid

Medially Palatine
bone of maxilla

Housed in lesser
wing of sphenoid

Annulus of Zinn

Zygomatic–N

Optic nerve (IInd N)

(Divides fissure)

Infraorbital–N

Meninges

Branches of
pterygopalatine
ganglion

Ophthalmic
artery

Upper

Middle

Inferior

Frontal
nerve Vth

Superior
div–IIIrd N

Ophthalmic
veins

Trochlear
nerve IVth

Nasociliary N
Vth N

Lacrimal
nerve Vth

Sympathetic
nerves

Recurrent
lacrimal artery

Inferior
div–IIIrd N

Superior
ophthalmic vein

VIth
Abducens N

Infraorbital
artery

Sympathetic
nerves

Inferior
orbital vein

FIGURE 1–10 Orbital apex.

The diameter of the canal is approximately 6.5 mm
but can enlarge with pathologic processes. The optic
strut separates the optic foramen from the superior
orbital fissure. 33 The optic nerve is vulnerable to
injury within the canal.34, 35
Although the medial aspect of the optic canal is primarily formed by the sphenoid, in approximately 50%
of cases posterior ethmoid air cells are present.25, 36

This variability should be considered when performing extracranial optic canal decompression and posterior ethmoidectomy during orbital decompression.
The posterior ethmoidal foramen is an important
landmark in the orbital apex. The medial optic canal
ring, the opening of the optic canal, is located 6 mm
posterior to the posterior ethmoidal artery.37

Periorbita
The periorbita is a thick fibrous layer that internally
lines the bony orbit. Anteriorly, it is continuous with
the periosteum, and forms the arcus marginalis, the
origin of the orbital septum. In the orbital apex,
the periorbita lines the superior orbital fissure, the

inferior orbital fissure, and optic canal, and is continuous with dura.
The periorbita provides a protective boundary for the
intraorbital contents from adjacent disease processes,
limiting spread of infections and tumors. The subperiorbital space is an excellent surgical plane because of
the ease with which the periorbita can be dissected from
the bone with minimal resulting hemorrhage.

Orbital Fascia
Studies by Koornneef38, 39 have shown that the globe
and orbital soft tissues are suspended in a complex,
organized connective tissue matrix (Fig. 1–11A). This
network is divided into three parts: Tenon’s capsule
(fascia bulbi), the extraocular muscles fascial sheaths
(Fig. 1–11A, 2), and the extensions and check ligaments that attach the muscle sheaths to the periorbita
and eyelids (Fig. 1–11A, 3).

Fascia Bulbi

Tenon’s capsule fuses with the bulbar conjunctiva
anteriorly, and is composed of fibroelastic tissue. It


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OPHTHALMIC FACIAL ANATOMY • 11

A

B

FIGURE 1–11 (A) Schematic arrangement of orbital fibrous septa. (Reprinted with permission from Koornneef 38.)
(B) Clinical photo of Whitnall’s ligament , right upper eyelid. This is a fibrous band found approximately 15 mm above the
superior tarsal border.

extends to the optic nerve posteriorly and is loosely
attached to the globe. Externally it attaches to the
fibrous septa of the orbital fat.

P

...

EARL
Anterior Tenon’s capsule,
when closed properly, provides the strongest barrier to extrusion of an orbital implant
following enucleation.
Fascial Sheaths (Fibroconnective Tissue Septa)
Throughout their entire length, the extraocular muscles are encompassed by a fascial sheath. The sheath
attaches to the orbital walls via check ligaments and to
the intraconal fat septa.19 Anteriorly, the muscles are
connected to the fascia, particularly at their insertion
onto the globe.

the levator, just at the transition from the aponeurotic to the muscular portions of the levator 42
(Fig. 1–11B).
Lockwood’s ligament arises from the fused fascia
of the inferior rectus and inferior oblique muscles.43 It
is a hammock-like suspensory ligament that is
strongest anterior to the inferior oblique muscle, and
will support the globe after floor removal and maxillectomy, provided that its medial and lateral attachments are intact. Orbital fat, however, is essential for
its function in globe support.44

EARL... The periorbita and medial

P

orbital strut, a ledge of bone between the
maxillary and ethmoidal sinuses, play a large
role in vertical globe support.45, 46

ORBITAL SOFT TISSUES
EARL ... This attachment can aid

P

surgeons in finding a muscle if it is lost
during strabismus surgery.

Fine radial septa also connect the optic nerve to
the medial, lateral, and inferior rectus muscles.40 The
intermuscular septum is formed by the muscle
sheaths prior to their insertion on the globe. Posterior to this, no common muscle sheath can be identified.38
The superior rectus and the levator palpebrae
superioris share an intermuscular fascia.41 The superior ophthalmic vein is also located in this complex.
Whitnall’s ligament arises from the fascial sheath of

Orbital Fat
Fat fills the space of the orbit not occupied by fascia,
the globe, muscles, nerves, vessels, and glands.
Orbital fat is more fibrous anteriorly, due to the
increased density of the fibrous framework, and more
lobular posteriorly.

PITFALL
Although it is an excellent surgical landmark,
orbital fat can be obstructive in deeper surgical dissection.


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12 • OCULOPLASTIC SURGERY: THE ESSENTIALS
medial and central fat pads are continuous, with the
valley of the inferior oblique dividing the two. The
central fat is separated from lateral fat pad by the
arcuate expansion of the inferior oblique muscle,
which courses inferotemporally.

P

...

EARL
The inferior orbital fat is an
excellent surgical landmark during transconjunctival inferior orbitotomy (Fig. 1–13).

FIGURE 1–12 Clinical photo showing preaponeurotic
fat pad, right upper eyelid.

Superior orbital fat is divided into two distinct
compartments, the preaponeurotic and the medial fat
pads (Fig. 1–12). They are separated by the trochlea.
The preaponeurotic fat pad, which is more yellow in
color, extends laterally over the lacrimal gland to the
superior edge of the lateral rectus muscle. 47 The
medial fat pad, being firmer and pale white in color, is
associated with the medial palpebral artery and the

infratrochlear nerve. Deeper anesthetic placement is
usually required for removal of this fat pad during
blepharoplasty. Because of their close relationship to
the trochlea, superior oblique palsy and Brown’s syndrome have been reported from injury during upper
eyelid blepharoplasty.48
The inferior orbital fat can be divided into three
compartments.49 The medial fat pad is separated from
the central fat by the inferior oblique muscle. The

The dissection plane can occur either preseptally,
remaining anterior to the orbital fat, or postseptally
to approach the inferior orbital rim.

Vasculature
The ophthalmic artery, the first branch of the internal
carotid artery, provides the major blood supply to the
orbit. The external carotid artery also contributes via
the middle meningeal and maxillary arteries.
The main venous drainage system of the orbit
occurs via the superior and inferior ophthalmic veins,
which lie within the connective tissue septa. The larger
superior ophthalmic vein (SOV) arises superomedially
near the superior oblique tendon with contributions
from the angular, supraorbital, and supratrochlear
veins. It travels near the medial aspect of the superior
rectus muscle, then enters the muscle cone and
receives branches from ciliary and superior vortex
veins. The SOV then travels beneath the superior rectus muscle along the lateral border of the muscle to
enter the superior orbital fissure and subsequently the
cavernous sinus. The SOV hammock is a connective

Preaponeurotic fat
Trochlea
Lacrimal
gland

Nasal fat pad

Lacrimal sac
Temporal
fat pad

Nasal fat pad
Arcuate
expansion
of inferior
oblique
muscle

Central
fat pad

Inferior oblique
muscle

FIGURE 1–13 Clinical compartments of anterior orbital fat.