6. Oculocutaneous Albinism (OCA):
• OCA is uncommon. Except for autosomal dominant OCA, all variants
are autosomal recessive.
There are two major forms:
1. tyrosinase-negative OCA characterized by total failure of melanin
formation (demonstrated by plucked hair bulbs failing to darken when
incubated with tyrosine),
2. tyrosinase-positive OCA, in which some pigmentation develops as
the patient ages and in which the hair bulbs darken in the presence of
tyrosine.
Tyrosinase-positive OCA is more common and embraces various
syndromes, including Prader–Willi, Hermansky–Pudlak, Chediak–
Higashi, and Cross–McKusick syndromes.
Clinical Manifestations In tyrosinase-negative OCA the skin is pink, the
hair is white, and the irides are translucent, giving a prominent red
reflex.
7. • In tyrosinase-positive OCA, the skin, hair, and eyes develop some pigment
as the patient ages. Light tanning may occur, the hair becomes flaxen-
yellow or red; in blacks, the skin becomes yellowish-brown with dark
freckles sometimes developing in sun-exposed areas.
Ocular Features:
Photophobia, decreased vision, and horizontal or rotary nystagmus,
sometimes with head-nodding, are found in both forms of OCA but are
more severe in tyrosinase-negative OCA.
The patients also have misrouting of the optic fibers at the chiasm.
The irides in tyrosinase-positive black patients may appear brown or tan,
otherwise, in both tyrosinase-positive and tyrosinase-negative OCA, they
are blue and transilluminate readily.
Sometimes in albinoidism (hypopigmentation of the hair and skin and a
positive hair bulb test), the irides transilluminate in a punctate pattern.
Increased visibility of the choroidal vessels, due to decreased amounts of
retinal pigment epithelium, is found, and macular hypoplasia may occur,
characterized by a normal perifoveal vasculature with absence of the
foveal pit and the pigment of the macula lutea.
Optic nerve hypoplasia is also common.
OCA patients have an increased incidence of strabismus and refractive
errors.
10. • Temporally located pits are usually associated with
serous macular detachment and, occasionally,
secondary macular edema and macular hole.
• Larger pits are associated with a higher frequency of
serous maculopathy.
• Macular edema or detachment occurs in about 40–60 %
of patients with optic disc pits.
• Central visual loss from these macular complications
develops at 30–40 years of age.
• Spontaneous reattachment is seen in about 25 % of
cases, but visual recovery has been observed to be
variable.
• The etiology of the intraretinal fluid associated with
optic pits remains controversial.
• Possible sources include vitreous cavity, subarachnoid
space, blood vessels at the base of the pit and orbital
space surrounding the dura.
13. Progressive Outer Retinal Necrosis
• Progressive Outer Retinal Necrosis is characterized by a rapid
progression of necrosis of the outer retina in immunocompromised
patients.
• The most common etiologic agent is Varicella Zoster Virus, Herpes
Simplex Virus.
• Progressive Outer Retinal Necrosis was described as an infectious
retinitis associated with recent cutaneous zoster infection, marked by
limited intraocular inflammation, predominant involvement of the
outer retina.
General Pathology and Pathophysiology:
• A hallmark feature of is the lack of intraocular inflammation.
• Deep necrosis can be present in any or multiple parts of the outer
retina. These lesions can rapidly progress to full thickness as well as
confluence.
• Serous retinal detachments can occur secondary to fluid leakage from
full thickness necrosis, often resolving with treatment leading to
disease inactivity.
14. Physical examination:
• large patches of yellow-white retinal opacification with necrosis of the deep retinal
layers.
• Multifocal lesions can progress rapidly to confluence without consistent direction of
disease spread.
• The majority of patients have a quiet anterior chamber and absence of vitreous cell; if
present, reaction is classically minimal.
• Other clinical features include a retinal vasculopathy with vascular sheathing and
occlusion and optic nerve abnormalities including hyperemia or edema.
• A large number of patients, approximately 70% by some studies, develop retinal
detachments.
• OCT is significant for not only outer retinal disorganization, consistent with necrosis of
the outer layers, but also hyper-reflectivity of the inner layers as well. Cystoid spaces
and foveal thickening can also be observed.
• Fundus autofluorescence classically shows stippled areas of mixed hyper- and hypo-
autofluorescence, indicative of adjacent "sick" RPE cells, accumulating lipofuscin (hyper-
autofluorescent) and RPE and adjacent photoreceptor death (hypo-autofluorescent).
Differential diagnosis:
• Infectious: CMV retinitis, ARN, Syphilitic retinitis, Toxoplasma retinochoroiditis,
tuberculosis, toxocariasis, fungal or bacterial endophthalmitis
• Inflammatory: Sarcoidosis, Behcet's, other retinal vasculitides Neoplastic: intraocular
lymphoma, leukemia, metastasis
• Progressive Outer Retinal Necrosis may appear similar to central retinal arterial
occlusion, but fragmentation of blood column within retinal vessels is absent in
Progressive Outer Retinal Necrosis and there is typical paravascular clearing.
16. Pyogenic granuloma (PG) refers to a benign vascular proliferation of
immature capillaries that is neither purulent nor granulomatous and is
also called lobular capillary hemangioma.
• PG presents as a lobulated raised lesion within the conjunctiva.
Associated conditions:
• predisposing factors, pyogenic granuloma is most commonly seen at a
traumatic wound site or near a suture line after surgery for chalazion,
pterygium, strabismus, retinopexy, enucleation
Pathology:
• PG is thought to represent an abnormal wound healing reaction.
Symptoms:
• Some discomfort or irritation may be felt
• Rapid growth usually lasts a few weeks.
• It ranges from a sessile, broad-based lesion to an abruptly elevated
growth.
• PGs are often pedunculated, with an underlying stalk of feeder blood
vessels and connective tissue.
17. Pyogenic Granuloma
Management:
Most PGs will resolve once
the primary inciting cause
such as a chalazion is
treated. Lubrication with
artificial tears and
occasionally topical
steroid eye drops can help
with symptom relief. If the
PG does not regress
within weeks or is causing
symptoms, simple excision
can be curative.
18. Cystinosis
The eyes are the second most
commonly affected extra-renal organ,
with cystine crystal deposits in the
corneas.
Cystine crystals can be observed in the
cornea after age 1.5–2 years and
diagnosis is cystinosis.
Pigmentary retinopathy consisting of
patches of depigmentation as an early
ocular finding and can result in impaired
color vision and night vision.
Progressive retinopathy and band
keratopathy occur later.
19. • The eyes are the second most commonly affected
extra-renal organ, with cystine crystal deposits in the
corneas.
• Cystine crystals can be observed in the cornea after age
1.5–2 years and are diagnostic of cystinosis.
• Pigmentary retinopathy consisting of patches of
depigmentation may sometimes be present as an early
ocular finding and can result in impaired color vision
and impaired night vision.
• Progressive retinopathy and band keratopathy occur
later in life in patients not treated with cysteamine eye
drops.
20.
21. Orbital cellulitis is defined as a serious
infection that involves the muscle and fat
located within the orbit. Orbital cellulitis
does not involve the globe itself, can occur at
any age, it is more common in the pediatric
population
Etiology
Orbital cellulitis most commonly occurs when
bacterial infection spreads from the
paranasal sinuses, most often from the
ethmoid sinus through the thin lamina
papyracea of the medial orbital wall.
It can also occur when an eyelid skin
infection or an infection in an adjacent area
spreads to the orbit or from an infection in
the blood stream. The drainage of the eyelids
and sinuses occurs through the orbital
venous system: superior and inferior orbital
veins that drain into the cavernous sinus. This
venous system is devoid of valves and for this
reason infection might spread, in preseptal
and orbital cellulitis, into the cavernous sinus
causing a sight threatening complication such
as cavernous sinus thrombosis.
22. The physical examination should include:
Best-corrected visual acuity (BCVA). Decreased vision might be indicative of optic nerve involvement or
could be secondary to severe exposure keratopathy or retinal vein occlusion.
Color vision assessment to assess the presence of optic nerve involvement.
Proptosis measurements using Hertel exophthalmometry.
Visual field assessment.
Assessment of pupillary function with particular attention paid to the presence of a relative afferent
pupillary defect (RAPD).
Ocular motility and presence of pain with eye movements: involvement of the III, IV, VI cranial nerve in
cases of cavernous sinus involvement.
Orbit exam should include documentation of direction of displacement of globe (e.g. a superior
subperiosteal abscess will displace the globe inferiorly), resistance to retropulsion on palpation,
unilateral or bilateral involvement
Measurement of intraocular pressure . Increased venous congestion may result increased IOP.
Slit-lamp biomicroscopy of the anterior segment to look for signs of exposure keratopathy in cases of
severe proptosis.
Dilated fundus exam will exclude or confirm the presence of optic neuropathy or retinal vascular
occlusion.
The differential diagnosis includes:
• Idiopathic inflammation/specific inflammation (e.g. orbital pseudo tumor, granulomatosis with
polyangiitis, sarcoidois)
• Neoplasia (e.g. lymphangioma, hemangioma, leukemia, rhabdomyosarcoma, lymphoma,
retinoblastoma, metastatic carcinoma)
• Trauma (e.g. retrobulbar hemorrhage, orbital emphysema)
24. Subconjunctival prolapse of orbital fat
• Intraconal orbital fat can herniate into the
subconjunctival space when Tenon's capsule is
violated spontaneously or after trauma or surgery.
• This process appears as a unilateral or bilateral,
elevated, compressible, yellow-orange mass with
visible lipid globules.
• It is most commonly located in the
superotemporal quadrant of the globe in elderly,
obese men.
