Ebook Vitreoretinal disorders in primary care: Part 1

Vitreoretinal Disorders
in Primary Care





Vitreoretinal Disorders
in Primary Care

Thomas H. Williamson


CRC Press
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Library of Congress Cataloging‑in‑Publication Data
Names: Williamson, Thomas H., author.
Title: Vitreoretinal disorders in primary care / Thomas H. Williamson.
Description: Boca Raton, FL : CRC Press, [2018] | Includes bibliographical references and index.
Identifiers: LCCN 2017014863| ISBN 9781138096547 (hardback : alk. paper) |
ISBN 9781138628113 (pbk. : alk. paper) | ISBN 9781315210773 (ebook)
Subjects: | MESH: Retinal Diseases--diagnosis | Retinal Diseases--therapy | Vitreous Body | Primary Health Care
Classification: LCC RE551 | NLM WW 270 | DDC 617.7/35--dc23
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Contents

Prefacexiii
Authorxv

1 Anatomy and examination of the eye
1
Embryology of the eye
1
Anatomy1
Vitreous1
Anatomical attachments of the vitreous to the surrounding structures
2
Retina2
Retinal pigment epithelium
4
Photoreceptor layer
4
Cones5
Ganglion cells
6
Nerve fibre layer
6
Inner limiting membrane
6
Retinal blood vessels
6
Bruch’s membrane
6
Choroid6
Investigation8
Visual acuity
8
Slit lamp
8

Optical coherence tomography
8
Inner segment and outer segment junction (ellipsoid layer)
9
Central retinal thickness
10
Subjective tests
10
References10
2 Posterior vitreous detachment
13
Introduction13
Symptoms14
Floaters14
Flashes15
Signs18
Detection of PVD
18
Shafer’s sign
19
Vitreous haemorrhage
19
Ophthalmoscopy21
Retinal tears
21
U tears
21
Atrophic round holes
23
v

Contents

Other breaks
23
Progression to retinal detachment
23
Peripheral retinal degenerations
24
Referral29
Posterior vitreous detachment
29
Medicolegal case
30
Missing the symptoms of posterior vitreous detachment
30
Error30
Errors30
References30
3 Vitreous haemorrhage
35
Introduction35
Aetiology35
Causes
37
Natural history
37
Erythroclastic glaucoma
38

Investigation38
Ultrasound40
Ultrasound features
40
Referral41
Vitreous haemorrhage non-diabetic
42
Medicolegal case
42
References43
4 Rhegmatogenous retinal detachment
45
Introduction45
Tears with posterior vitreous detachment
45
Breaks without posterior vitreous detachment
49
Natural history
49
Chronic RRD
50
Clinical features
51
Anterior segment signs
52
Signs in the vitreous
52
Subretinal fluid accumulation
52
Retinal break patterns in RRD

54
Macula off or on
54
Flat retinal breaks
58
Retinopexy58
Cryotherapy59
Laser59
Rhegmatogenous retinal detachment
59
Principles of surgery
60
Pars plana vitrectomy
60
Posturing63
Non-drain procedure
63
Pneumatic retinopexy
67
Success rates
67

vi


Contents

Causes of failure
67
Proliferative vitreoretinopathy

67
Introduction67
Pathogenesis68
Clinical features
68
Introduction68
Grading68
Risk of PVR
70
Surgery70
Relieving retinectomy
70
Success rates
70
Surgery for redetachment
72
Secondary macular holes
74
Detachment with choroidal effusions
74
Medicolegal cases
74
Case 1
74
Errors75
Case 2
75
Errors75
Case 3
75

Errors75
References76
5 Different presentations of rhegmatogenous retinal detachments
81
Age-related RRD from PVD
81
Atrophic hole RRD with attached vitreous
81
Pseudophakic RRD
81
Aphakic RRD
83
Retinal dialysis
84
Clinical features
84
Giant retinal dialysis
86
Par ciliaris tear
86
Giant retinal tear
86
Clinical features
86
Stickler’s syndrome
88
Other eye
89
Retinal detachment in high myopes
89

Clinical features
89
Retinoschisis-related retinal detachment
89
Clinical features
89
Infantile retinoschisis
92
Senile retinoschisis
93
Differentiation of retinoschisis from chronic RRD
93
Retinal detachment in retinoschisis
93
Juvenile retinal detachment
94
Atopic dermatitis
95
Refractive surgery
95
Congenital cataract
95
vii


Contents

Others95
References96
6 Macular disorders

101
Introduction101
Idiopathic macular hole
101
Clinical features
101
Introduction101
Watzke–Allen test
102
Grading102
Natural history
114
Optical coherence tomography
114
Secondary macular holes
114
Lamellar and partial thickness holes
117
Pars plana vitrectomy
117
Microplasmin119
Referral119
Macular pucker and vitreomacular traction
121
Clinical features
121
Other conditions
129
Secondary macular pucker
129

Success rates of surgery
131
Specific complications of surgery
132
Membrane recurrence
132
Referral132
Age-related macular degeneration
136
Clinical features
136
Simplified AREDS scoring system
136
Vitreous haemorrhage and choroidal neovascular membranes
137
Referral137
Pneumatic displacement of subretinal haemorrhage
138
Referral139
Choroidal neovascular membrane not from AMD
139
Introduction139
References141
7 Diabetic retinopathy
147
Introduction147
Diabetic retinopathy
147
Introduction147
Diabetic retinopathy grading

147
Diabetic vitreous haemorrhage
148
Clinical features
149
Diabetic retinal detachment
151
Clinical features
151
Success rates
154
Diabetic maculopathy
155
Retinal vein occlusion
155
Sickle cell disease
156
viii


Contents

Introduction156
Types of sickle cell disease
156
Systemic investigation
156
Inheritance and race
156
Systemic manifestations

157
Ophthalmic presentation
157
Visual outcome
160
Screening160
Survival160
Retinal vasculitis
160
Central retinal artery occlusion
161
Medicolegal case
161
References161
8 Trauma
165
Introduction165
Classification165
Contusion injuries
166
Clinical presentation
166
Types of retinal break
167
Dialysis167
Par ciliaris tears
168
Ragged tear in commotio retinae
168
Giant retinal tears

169
Visual outcome
169
Rupture170
Clinical presentation
170
Visual outcome
172
Penetrating injury
172
Clinical presentation
172
Endophthalmitis173
Retinal detachment
173
Visual outcome
173
Trauma scores
173
Intraocular foreign bodies
174
Clinical presentation
174
Diagnostic imaging
174
IOFB materials
175
Visual outcome
176
Perforating injury

176
Sympathetic ophthalmia
177
Proliferative vitreoretinopathy
177
Phthisis bulbi
177
Referral178
Medicolegal case
179
Case 1
179
Case 2
179
References179
ix


Contents

9 Complications of anterior segment surgery
185
Introduction185
Dropped nucleus
185
Clinical features
185
Success rates
187
Intraocular lens dislocations

188
Clinical presentation
188
Post-operative endophthalmitis
188
Clinical features
188
Infective organisms
190
Antibiotics191
Success rates
191
Chronic post-operative endophthalmitis
192
Needle-stick injury
192
Clinical features
192
Intraocular haemorrhage
192
Retinal detachment
193
Chronic uveitis
194
Post-operative vitreomacular traction
194
Post-operative choroidal effusion
194
Medicolegal case
195

References195
10 Uveitis and allied disorders
199
Non-infectious uveitis of the posterior segment
199
Referral for vitrectomy
199
Vitreous opacification
201
Retinal detachment
201
Cystoid macular oedema
201
Hypotony202
Infectious uveitis
202
Acute retinal necrosis
202
Clinical features
202
Cytomegalovirus retinitis
203
Clinical features
203
Fungal endophthalmitis
205
Clinical features
205
Other infections
207

Ocular lymphoma
208
Clinical features
208
Visual outcome and survival
209
Paraneoplastic retinopathy
209
References209
11 Miscellaneous conditions
215
Vitrectomy for vitreous opacities
215

x


Contents

Vitreous anomalies
216
Persistent hyperplastic primary vitreous
216
Asteroid hyalosis
216
Amyloidosis217
Retinal haemangioma and telangiectasia
217
Optic disc anomalies
218

Optic disc pits and optic disc coloboma
218
Morning glory syndrome
218
Retinochoroidal coloboma
222
Marfan’s syndrome
222
Retinopathy of prematurity
223
Uveal effusion syndrome
224
Clinical features
224
Terson’s syndrome
226
Disseminated intravascular coagulation
226
Retinal prosthesis
226
References226
Index231

xi





Preface

The specialism of vitreoretinal surgery has continued to grow in the last 50 years. The main
operation of pars plana vitrectomy is now the second most common intraocular operation after
cataract surgery. The disorders treated by this surgery are often emergency conditions. The
conditions are complex and varied; obtaining or maintaining knowledge of these conditions
can be difficult, especially for those in the front line of healthcare provision. This can leave
patients vulnerable to error in clinical diagnosis and management. Inappropriate delay in referral can lead to poorer outcomes in these patients.
This book has been written to aid those in the primary care professions to recognise vitreoretinal conditions and provide advice on referral practices. The referral patterns are only a
guide, and local practices may vary. It has been assumed for the purposes of the book that there
is good access to healthcare facilities and specialist opinion. The recommendations are generalised, and there will be individual patients who require a referral approach different from the
one described.
Drawing from my 20 years as an expert witness, I have created fictional medicolegal cases to
illustrate how referral may play a part in any potential litigation. These show some of the pitfalls
that primary care professionals may experience.
I would like to acknowledge the help of Robin Cannon for the three-dimensional graphics,
Professor John Marshall for the histological images of the retina, Dermott Roche for optical
coherence tomography images and Matt Robertson for the wide-angle retinal images.

xiii





Author

Tom Williamson is a vitreoretinal surgeon located in central London, UK. He has been performing vitreoretinal operations for 30 years and has published widely on the subject. His
books are the primary training manuals in vitreoretinal surgery internationally. He has written this book for primary care physicians allowing for informed and safe care of patients with
vitreoretinal disorders.

xv





1

Anatomy and examination
of the eye

EMBRYOLOGY OF THE EYE
• 6–7 weeks of gestation:
The optic cup develops from the optic vesicle and consists of two layers of ectoderm, the
outer becoming the retinal pigment epithelium (RPE) and the inner, the neurosensory
retina.
• 13 weeks:
The receptor cells appear.
• 1.5–3 months:
The RPE becomes pigmented.
• 5.5 months:
The adult retinal structure can be seen.
• 3–4 months after birth:
The macula is formed.

ANATOMY
VITREOUS
The vitreous fills the internal space of the eye posterior to the lens and its zonular fibres and has
a volume in emmetropia of about 4 mL, which increases to 10 mL in highly myopic eyes. The
vitreous is a hypocellular viscous fluid that consists of the following:

• 99% water content
• Hyaluronic acid
• Type 2 collagen fibrils
The cortical part of the vitreous gel has a higher content of hyaluronic acid and collagen
compared with the less dense central gel. There are anterior and posterior hyaloid membranes and a central tubular condensation called Cloquet’s canal. Removal of the gel does
not adversely affect the eye apart from a poorly understood increased risk of nuclear sclerotic
cataract.

1


Anatomy and examination of the eye

ANATOMICAL ATTACHMENTS OF THE VITREOUS TO THE
SURROUNDING STRUCTURES
• The posterior hyaloid membrane adheres to the internal limiting membrane (ILM) of the
retina. This adhesion breaks down in posterior vitreous detachment.
• The vitreous base is a zone of adhesion of the vitreous to the retina and pars plana that is
3–4 mm wide and lying across the ora serrata. It is an area of strong adhesion and is not
usually separated even in surgical procedures.
• Weigert’s ligament is a circular zone of adhesion of the anterior vitreous, 8–9 mm in
diameter, to the posterior lens capsule.
• The posterior hyaloid membrane and the slightly expanded posterior limit of Cloquet’s
canal meet around the margin of the optic disc. During posterior vitreous detachment,
evidence of this adhesion is seen as Weiss’s ring.
• A circle of relatively increased adhesion to the retina may be present in the parafoveal
area and implicated in macular hole formation (Figures 1.1 and 1.2).

RETINA
The retina is divided into regions.

• The macula between the temporal vascular arcades serves approximately 20° of visual
field.
• The fovea is a central darkened area with a pit called the foveola.
The cones, the receptors for detailed vision, are densest at the fovea, at 15,000/mm2, with
4,000–5,000/mm 2 in the macula. There are 6 million cones and 120 million rods in total
(Figure 1.3).

Figure 1.1  Cutaway of the eye showing the vitreous cavity filled with vitreous gel.

2


Retina

Vitreous base

Weigert’s ligament
Berger’s space
Cloquet’s canal
Martergiani’s space
Vitreous base

Figure 1.2  Vitreous anatomy is shown.

Periphery

Macula
Optic disc

Fovea

Figure 1.3  Landmarks of the normal retina are shown.

The retina is organised into four layers of cells and two layers of neuronal connections. It has
a structural cell called the Muller cell, which extends through all the layers. These are as follows:
•
•
•
•
•

Specialised glial cells
A sink of ions during depolarisation of receptors
Layer involved in cone neuroprotection
Layer controlling vascular permeability and haemostasis
Layer involved in pigment recycling

There are astrocytes and microglial cells in addition in the retina (Figure 1.4).
3


Anatomy and examination of the eye

Inner segments
Outer segments

Figure 1.4  Anatomical layers of the retina are shown. GCL, ganglion cell layer; IPL, inner plexiform
layer; INL, inner nuclear layer; NFL, nerve fibre layer; OPL, outer plexiform layer; ONL, outer nuclear layer.

RETINAL PIGMENT EPITHELIUM

The RPE is a single layer of pigmented cuboidal epithelial cells, which look after the function of
the receptors by performing the following:
•
•
•
•
•

Absorbing stray light (using melanin pigment)
Transporting metabolites between the receptors and the choroid
Providing a blood retinal barrier
Regenerating the visual pigments
Phagocytosing the receptor outer segments, leading to lipofuscin production

PHOTORECEPTOR LAYER
The photoreceptor transduces light into neuronal signals. The action of light closes gated cation
channels leading to hyperpolarisation of the cell. Two types of photoreceptor exist, the rods
predominantly in the periphery and absent from the fovea and the cones concentrated at the
macula.
The receptors consist of two parts:
• Outer segments
Light is absorbed by the visual pigments in stacked discs, separate in the rods (1,000 in
number), interconnected in the cones. This is joined to the inner segment by the cilium.
4


Retina

• Inner segments
These consist of an inner myoid, which contains the Golgi apparatus and ribosomes for

making cell structures, and an outer ellipsoid, which contains mitochondria for energy
production. These connect to the nucleus by the outer connecting fibre. The inner
connecting fibre connects to the synaptic region. The latter has synapses arranged as
triads with connections to one bipolar cell and two horizontal cells. In cones, there may
be up to 20 triads, whereas the rods have only one.

CONES
Cones provide high-resolution colour vision in photopic conditions. They react quickly and
recover rapidly to different light stimuli. Three types of cone photoreceptor exist in the
human eye with different opsin proteins bound to a common chromophore (11-cis-retinal).
The three types provide sensitivities which peak at different light wavelengths with short
S cones at 420 nm (blue), middle M cones at 530 nm (green) and long L cones at 560 nm
(red) (Figure 1.5).
• Outer limiting layer
This consists of junctional complexes from the Muller cells and photoreceptors and is
located at the inner connecting fibres.
• Outer plexiform layer
The cell processes of the horizontal cells and bipolar cells synapse with the receptors.
• Intermediary neurons
• Inner nuclear layer
This contains the cell bodies of the bipolar cells, Muller cells, amacrine cells and
horizontal cells.
• Inner plexiform layer
The bipolar cells axons pass through, synapsing with the amacrine cells, which help
process the neuronal signals to the ganglion cells.

Figure 1.5  Fovea has a high density of cones.

5

Anatomy and examination of the eye

GANGLION CELLS
• Ganglion cell layer
The cell bodies of the ganglion cells are found here. These cells have gathered preprocessed
information from the other retinal cells. At the macula, there is one ganglion cell to one
receptor, but on average in the whole retina, there is one for 130 receptors.

NERVE FIBRE LAYER
The nerve fibres of the ganglion cells on the inner surface of the retina pass tangentially towards
the optic nerve.

INNER LIMITING MEMBRANE
The ILM is a tough membrane laid down by the Muller cells with connections to the hyaloid
membrane of the vitreous.

RETINAL BLOOD VESSELS
The central retinal artery supplies the neural retina with the exception of the photoreceptors,
which are supplied by the choriocapillaris. The former is an end artery system with a single
draining vessel, the central retinal vein. Both the central retinal artery and the vein have four
main branches, which divide at the optic disc to supply nasal and temporal quadrants. At the
posterior pole, there is a capillary network at the level of the nerve fibre layer and the outer
plexiform layer. In the periphery, there is one capillary network at the inner nuclear layer. The
capillary endothelium forms the inner retinal blood retinal barrier by having tight intercellular
junctions (Figure 1.6).

BRUCH’S MEMBRANE
Bruch’s membrane is a pentilaminar structure partly representing the basement membranes of
the RPE and the choriocapillaris. It is of ectodermal and mesodermal origins. The accumulation

of damage in Bruch’s membrane is seen in age-related macular degeneration.

CHOROID
This is a vascular layer (large vessels are outer and the capillaries are inner) with a highly relative blood flow and low oxygen utilisation (3%). It supplies the RPE and photoreceptors. The
highly anastomotic and fenestrated capillaries are arranged into lobules and are supplied by the
posterior ciliary arteries and drained by the vortex veins.

6


Retina

Figure 1.6  At the posterior pole, there is a capillary network at the level of the nerve fibre layer and
the outer plexiform layer. In the periphery, there is one capillary network at the inner nuclear layer. The
capillary endothelium forms the inner retinal blood retina barrier by having tight intercellular junctions.

7


Anatomy and examination of the eye

INVESTIGATION
VISUAL ACUITY
LogMar values are recommended for the ease of analysis of data for surgical audit and governance. This can be measured by the Snellen chart or Early Treatment Diabetic Retinopathy
Study chart but requires full refractive correction.

SLIT LAMP
Goldman tonometry, various contact lenses or three-mirror contact lenses can be used. The
operator can visualise the vitreous by looking behind the posterior lens. The slit lamp allows
the use of specialised lenses for the examination of the retina, e.g. super-field 90D or 60D noncontact lenses.

OPTICAL COHERENCE TOMOGRAPHY
Optical coherence tomography (OCT), first developed for ophthalmic imaging in the 1990s1
is invaluable in the retinal clinic. OCT scanning provides two-dimensional cross sections of
the retina from which three-dimensional reconstructions can be created.2 Conceptually, OCT
operates on the same physical principles as an ultrasound scan except it uses light as the carrier
signal. The spatial resolution of an OCT is conventionally 10–20 MHz.
The source of light in an OCT is produced by a superluminescent diode, a femtosecond laser,
or more recently using white light.3
OCT works by splitting a beam of light into two arms – a reference arm and a sampling arm.
First-generation OCTs are time-domain OCT, so named because the length of the reference arm is varied with time, in order to correlate with the back-reflected sample arm. This is
achieved with the use of an adjustable mirror of known distance within the device. The sample
arm is focused onto the retina with the use of an in-built 78D lens. The sample beam is reflected
off the structures in the eye and is recombined with the reference beam by using a Michelson
interferometer within the unit. A single cycle of this process yields one A-scan. This single scan
is composed of data on the distance the sample arm has travelled and the back reflectance and
backscatter of the beam. Tissue layers at varying depths and optical characteristics produce differing reflective intensities (Figure 1.7).

Figure 1.7  Normal OCT image of the macula. The foveal dip is shown centrally, with the nasal macular
retina on the right.

8