1What are the two main divisions of the eyeball?
Anterior segment and posterior segment
2What structure forms the boundary between the anterior and posterior segments?
Lens-iris diaphragm
3Does the conjunctiva cover the cornea?
No, the cornea must remain transparent.
4Where does the conjunctiva terminate?
Limbus, the corneoscleral junction
5What is the limbus?
Junction between the cornea and sclera
6What is the main function of the cornea?
Refracts light and transmits it into the eye
7What are the two main refractive structures of the eye?
Cornea and lens
8What is the total refractive power of the eye?
60 diopters
9What is the refractive power of the cornea?
40–43 diopters
10What percentage of focusing power does the cornea contribute?
Approximately 2/3 or up to 85%
11What is the refractive power of the lens?
17–20 diopters
12What percentage of focusing power does the lens contribute?
Approximately 1/3
13What is the diameter of the adult cornea?
Approximately 11 mm
14What is the vertical diameter of the cornea?
11 mm
15What is the horizontal diameter of the cornea?
11.5 mm
16What is the central corneal thickness?
Approximately 500 μm
17What is the peripheral corneal thickness?
Approximately 650 μm
18What is the approximate corneal thickness along its margins?
1 mm
19What instrument measures central corneal thickness?
Pachymetry
20What imaging technique can measure corneal thickness?
Optical coherence tomography (OCT)
21What are the three main cellular layers of the cornea?
Epithelium, stroma, and endothelium
22What are the two auxiliary acellular layers of the cornea?
Bowman's layer and Descemet's membrane
23What are the five corneal layers from anterior to posterior?
Epithelium, Bowman's layer, stroma, Descemet's membrane, endothelium
24What mnemonic represents the five corneal layers?
ABCDE
25What is the order of the ABCDE corneal layers?
Anterior epithelium, Bowman's layer, central stroma, Descemet's membrane, endothelium
26What is Dua's layer?
Thin pre-Descemet's layer anterior to Descemet's membrane
27What makes the cornea transparent?
Uniform collagen arrangement, avascularity, lack of pigment, and deturgescence
28Why is the sclera white?
Irregular arrangement of collagen fibers
29What is corneal deturgescence?
Relative dehydration of corneal tissue
30What is the vascular status of the normal cornea?
Avascular
31What are the three nutritional sources of the cornea?
Limbal vessels, aqueous humor, and tears
32Where does the cornea obtain most of its oxygen?
Atmosphere through the tear film
33Which cranial nerve supplies corneal sensation?
Ophthalmic division (V1) of the trigeminal nerve
34What is the central 5 mm of the cornea responsible for?
Most of the corneal refractive power
35What type of epithelium covers the anterior cornea?
Stratified squamous nonkeratinizing epithelium
36How many layers does the corneal epithelium have?
Approximately 5 layers
37What is the approximate thickness of the corneal epithelium?
50 μm
38What happens if corneal epithelium becomes keratinized?
Corneal haziness and blurred vision
39What covers the anterior corneal epithelial surface?
Microvilli and microplicae
40What is the function of epithelial microvilli?
Help maintain interaction with the tear film
41What are the three layers of the tear film from outer to inner?
Lipid, aqueous, and mucin
42Which cells secrete the mucin layer?
Goblet cells
43Where are goblet cells most numerous?
Conjunctival fornices
44What is the function of the mucin layer?
Promotes tear film adherence to the cornea
45How many layers of superficial epithelial cells are present?
Two-cell layer
46What is the morphology of superficial epithelial cells?
Flattened and dense, with fewer organelles
47What is the morphology of wing cells?
Polyhedral cells
48Where are wing cells located?
Above the basal cell layer
49What is the basal germinal layer composed of?
Single layer of cuboidal to columnar cells
50What is the approximate height of basal epithelial cells?
18 μm
51How do corneal epithelial cells regenerate?
Basal cells multiply through mitosis and migrate superficially
52How long does complete corneal epithelial regeneration take?
Less than one week
53How quickly can a partial epithelial defect heal?
Approximately two days or overnight
54What is the first acellular layer of the cornea?
Bowman's layer
55What is another name for Bowman's layer?
Anterior limiting layer or Bowman's membrane
56What separates the epithelium from the stroma?
Bowman's layer
57What is the approximate thickness of Bowman's layer?
10 μm
58What is Bowman's layer composed of?
Densely packed, randomly arranged collagen fibrils
59What happens when Bowman's layer is destroyed?
Healing occurs through scarring
60What is the consequence of an abrasion extending into Bowman's layer?
Corneal scarring
61Does an epithelial abrasion confined above Bowman's layer normally scar?
No
62What is the main function of the corneal stroma?
Provides corneal strength and shape
63What percentage of the cornea is composed of stroma?
Approximately 90%
64What is another name for the stroma?
Substantia propria
65How many successive lamellae compose the stroma?
Approximately 200–300
66What are corneal lamellae composed of?
Regularly arranged collagen fibrils embedded in extracellular matrix
67What is the major extracellular matrix component of the stroma?
Sulfated glycosaminoglycans (GAGs)
68What cells produce stromal collagen and extracellular matrix?
Keratocytes
69What is the main function of keratocytes?
Maintain stromal shape and strength
70What is the normal cellularity of the corneal stroma?
Sparsely cellular
71What is responsible for corneal pain sensation?
Nerve fibers
72What is the diameter of corneal collagen fibrils?
Approximately 20–60 nm
73How does regular collagen spacing maintain corneal transparency?
Minimizes light scattering
74What happens when stromal collagen arrangement is disrupted?
Light dispersion, corneal haze, and blurred vision
75What is the second acellular layer of the cornea?
Descemet's membrane
76What is another name for Descemet's membrane?
Posterior limiting layer
77What separates the stroma from the endothelium?
Descemet's membrane
78Which cells produce Descemet's membrane?
Corneal endothelial cells
79How thick is Descemet's membrane during childhood?
Approximately 5 μm
80How thick is Descemet's membrane during adulthood?
Approximately 8–10 μm
81What is the strongest layer of the cornea?
Descemet's membrane
82What is the clinical landmark marking the termination of Descemet's membrane?
Schwalbe's line
83What procedure uses Schwalbe's line as a landmark?
Gonioscopy
84What is the innermost layer of the cornea?
Endothelium
85What is the morphology of corneal endothelial cells?
Flattened hexagonal cells
86How many layers compose the corneal endothelium?
Single layer
87What is the approximate thickness of the endothelium?
5–6 μm
88What is the main function of the corneal endothelium?
Maintains corneal transparency by regulating stromal hydration
89What happens when endothelial cell density decreases?
Reduced pump function and increased stromal hydration
90What is the consequence of increased stromal hydration?
Corneal edema and loss of transparency
91What are endothelial cells called when they vary in size?
Polymegathism
92What is pleomorphism in corneal endothelium?
Variation in endothelial cell shape
93What is the normal appearance of young corneal endothelial cells?
Uniform hexagonal cells
94What happens to endothelial cells with aging?
Cell density decreases and cell shapes become irregular
95What is the afferent nerve pathway of the corneal blink reflex?
CN V1
96Where do numerous free nerve endings terminate?
Corneal epithelium
97What dye is used to identify corneal epithelial defects?
Fluorescein
98What color does fluorescein produce under cobalt blue illumination?
Green
99What examination can detect corneal epithelial defects?
Slit-lamp examination
100What syndrome results from disturbance of the epithelial basement membrane?
Recurrent corneal erosion syndrome
101What behavior can precipitate recurrent corneal erosion?
Rubbing the eyes
102What is the main clinical consequence of central corneal scarring?
Reduced visual acuity
103What is the main treatment for severe corneal scarring?
Penetrating keratoplasty
104What is microbial keratitis?
Infectious inflammation of the cornea
105What organisms can cause microbial keratitis?
Bacteria, fungi, viruses, Acanthamoeba, Nocardia, Microsporidia, and Pythium
106What is the main function of the cornea in vision?
Acts as the transparent optical window of the eye
107How many corneal pathology cases occur annually according to the lecture?
Approximately 2 million
108What percentage of blindness is attributed to trauma and infection in the lecture?
Nearly 5%
109Why are fungal keratitis outcomes generally poorer?
Higher perforation rates and greater need for surgical intervention
110How much more expensive is fungal keratitis treatment according to the lecture?
Approximately three times more expensive
111What is hyperemia?
Redness and congestion of conjunctival peripheral vessels
112What condition is commonly associated with hyperemia?
Mild conjunctivitis
113What is ciliary injection?
Redness of ciliary vessels around the limbus
114What does ciliary injection suggest?
Corneal disease or anterior segment inflammation
115What are common symptoms of corneal disease?
Blurred vision, photophobia, pain, tearing, itchiness, and discharge
116What causes photophobia in corneal disease?
Numerous corneal nerve endings
117What causes pain in corneal disease?
Defect or injury of the corneal epithelium
118What is a corneal ulcer?
Corneal defect involving the stroma beyond Bowman's membrane
119What happens when a corneal ulcer violates Bowman's membrane?
Healing occurs with scarring
120Does a corneal ulcer usually take up fluorescein?
Yes, due to the epithelial defect
121Are corneal ulcers usually infectious?
Yes, although sterile exceptions occur
122What is an example of a sterile corneal ulcer?
Vernal catarrh-associated ulcer
123What characterizes a corneal ulcer clinically?
Corneal defect with stromal infiltrates and possible pus or tissue melting
124What does a thin ulcer center with thicker surrounding margins indicate?
Corneal ulceration
125Why are central corneal ulcers dangerous?
Risk of impending corneal perforation
126What can corneal perforation cause?
Aqueous leakage and risk of endophthalmitis
127What are risk factors for corneal ulcers?
Trauma, corticosteroid use, dry eyes, immunocompromise, diabetes, and contact lens wear
128Which infection is particularly associated with contact lens use?
Pseudomonas
129Which bacterium causes rapid corneal melting?
Pseudomonas aeruginosa
130What is the characteristic progression of Pseudomonas keratitis?
Rapid progression and corneal melting
131Why is Pseudomonas keratitis particularly dangerous?
Rapid ulceration and possible anterior chamber penetration
132Which bacteria can infect an intact corneal epithelium?
Neisseria gonorrhoeae, Haemophilus, Listeria, and Corynebacterium diphtheriae
133Which bacteria commonly cause secondary infection after epithelial injury?
Staphylococcus and Streptococcus
134What are common causes of bacterial keratitis?
Trauma, contact lens wear, and epithelial disruption
135What is hypopyon?
Pus accumulation in the anterior chamber
136What does hypopyon suggest in microbial keratitis?
Severe infection or possible endophthalmitis
137What are typical bacterial ulcer margins?
Well-defined margins with a flat profile
138When do bacterial keratitis symptoms typically manifest?
Approximately 3–5 days after infection
139What discharge is commonly associated with bacterial keratitis?
Purulent discharge
140What are typical fungal ulcer margins?
Serrated, ill-defined margins with a raised profile
141Which population is particularly at risk for fungal keratitis?
Farmers exposed to vegetative trauma
142What is a common cause of fungal keratitis after trauma with plant material?
Fusarium
143Which fungus commonly involves the deeper corneal stroma?
Aspergillus
144Which fungus is associated with immunocompromised patients?
Candida
145Which fungus is common in the southern Philippines according to the lecture?
Fusarium
146Which fungus is common in the northern and eastern Philippines according to the lecture?
Aspergillus
147What are risk factors for fungal keratitis?
Vegetative trauma and corticosteroid use
148What are early signs of fungal keratitis?
Mild stromal haze and pseudodendrites
149What is a pseudodendrite?
Branching, twig-like corneal lesion
150Which fungal medication is mentioned for Aspergillus keratitis?
Natamycin with fluconazole
151Which antifungal medication is mentioned for Candida keratitis?
Amphotericin B
152Which antifungal is commonly used for Fusarium keratitis?
Natamycin
153What is Acanthamoeba keratitis?
Protozoal corneal infection
154Which patients commonly develop Acanthamoeba keratitis?
Contact lens wearers
155What is a characteristic symptom of Acanthamoeba keratitis?
Severe ocular pain
156Why is Acanthamoeba keratitis difficult to treat?
No specific treatment is available according to the lecture
157What is the primary complaint in herpes simplex keratitis?
Pain
158Which HSV type commonly causes ocular herpes?
HSV type 1
159Which HSV type is sexually transmitted and rarely causes ocular disease?
HSV type 2
160How is herpes simplex transmitted?
Through bodily fluids and saliva
161Where does herpes simplex remain dormant after initial infection?
Nerves supplying the eye and skin
162What can reactivate herpes simplex?
Stress, heat, trauma, hormonal changes, fever, and certain medications
163Which patients are more likely to experience recurrent HSV infection?
Immunocompromised patients
164What are the common symptoms of herpes simplex keratitis?
Pain, red eye, tearing, photophobia, irritation, and decreased vision
165Is discharge typically present in epithelial herpes simplex keratitis?
No
166What happens to corneal sensitivity in herpes simplex keratitis?
Decreased corneal sensitivity or hypoesthesia
167What is the characteristic lesion of epithelial herpes simplex keratitis?
Dendritic ulcer
168What are the characteristic features of HSV dendritic lesions?
Linear branching patterns with terminal bulbs
169What diagnostic method identifies HSV dendritic ulcers?
Slit-lamp examination with fluorescein staining
170Does epithelial HSV keratitis violate Bowman's membrane?
No
171Does uncomplicated epithelial HSV keratitis usually scar?
No
172How does herpes zoster ophthalmicus differ from herpes simplex keratitis?
Zoster produces dermatomal blisters; HSV produces dendritic ulcers
173When should HSV keratitis be referred according to the lecture?
Ulcer over 3 mm, central ulcer, or one-eyed patient
174What antiviral medications are mentioned for HSV keratitis?
Acyclovir and ganciclovir
175How frequently are topical antiviral medications administered in the lecture?
Five times daily
176What did the Herpetic Eye Disease Study (HEDS) investigate?
Treatments for severe ocular herpes
177What oral acyclovir regimen is mentioned in HEDS?
400 mg four times daily
178What was the major finding of HEDS regarding oral acyclovir?
Reduced recurrence of ocular herpes
179When may corneal debridement be used in HSV keratitis?
To remove diseased epithelial cells
180What is the main indication for corneal transplantation in HSV disease?
Permanent corneal scarring from severe recurrent infection
181What causes viral keratitis in the lecture?
Adenovirus
182What is subepithelial keratopathy?
Corneal involvement beneath an intact epithelium
183Does subepithelial keratopathy take up fluorescein?
No
184When may blurred vision develop after acute viral conjunctivitis?
Approximately one week later
185What is the chief complaint in viral keratitis?
Tearing
186Is pain typical of subepithelial viral keratopathy?
No, because the epithelium remains intact
187What is a true anterior ocular emergency involving the cornea?
Chemical injury
188What is the immediate first aid for chemical eye injury?
Immediate copious irrigation with water or saline
189Which is more destructive to the eye: acid or alkali burns?
Alkali burns
190What type of necrosis is caused by alkali burns?
Liquefactive necrosis
191Why do alkali burns penetrate deeply?
They interact with cellular membrane lipids and cause tissue softening
192What type of necrosis is caused by acid burns?
Coagulative necrosis
193Why do acid burns generally penetrate less deeply?
Protein coagulation creates a barrier to further penetration
194Which chemicals can cause alkali burns?
Lye, cement, plaster, and household cleaners
195How long should chemical eye irrigation continue initially?
At least 30 minutes
196What solutions can be used for chemical eye irrigation?
Saline, lactated Ringer's solution, or clean water
197What should be done with the conjunctival fornices after chemical exposure?
Sweep with a wetted cotton applicator to remove particles
198Should acid be used to neutralize an alkali burn?
No, never use the opposite chemical to neutralize a burn
199What is a poor prognostic sign in ocular chemical burns?
More than 50% conjunctival or over 6 clock hours of limbal involvement
200What are severe chemical burn findings?
Conjunctival blanching, chemosis, corneal edema, opacification, and increased IOP
201What is hyphema?
Blood accumulation in the anterior chamber
202What is the primary cause of traumatic hyphema?
Blunt or direct ocular trauma
203What is the chief complaint of hyphema?
Blurred vision
204What is the most important complication of hyphema?
Rebleeding
205When does rebleeding commonly occur after hyphema?
3–5 days after injury
206What percentage of hyphema cases may rebleed according to the lecture?
Approximately 30%
207What is the grading of hyphema based on?
Amount of blood layering in the anterior chamber
208What characterizes Grade 0 hyphema?
No layered blood; red blood cells only
209What characterizes Grade 1 hyphema?
Blood occupying less than one-third of the anterior chamber
210What characterizes Grade 2 hyphema?
Blood occupying one-third to one-half of the anterior chamber
211What characterizes Grade 3 hyphema?
Blood occupying one-half to less than the entire chamber
212What characterizes Grade 4 hyphema?
Total hyphema
213What is a complication of uncontrolled hyphema?
Glaucoma
214What can blood staining of the cornea cause?
Permanent corneal opacity and visual impairment
215What is welder's keratitis?
UV-induced corneal epithelial injury
216What causes welder's keratitis?
Unprotected exposure to welding or tanning-lamp ultraviolet radiation
217When do symptoms of welder's keratitis typically develop?
6–12 hours after exposure
218What are symptoms of welder's keratitis?
Pain, tearing, photophobia, and foreign-body sensation
219What is corneal abrasion?
Superficial injury to the corneal epithelium
220Does a simple corneal abrasion involve Bowman's membrane?
No
221Does a simple corneal abrasion usually cause scarring?
No
222What is the chief complaint of corneal abrasion?
Pain
223What are typical symptoms of corneal abrasion?
Pain, photophobia, tearing, and foreign-body sensation
224How is corneal abrasion diagnosed?
Slit-lamp examination with fluorescein staining
225What color does an epithelial abrasion appear under cobalt blue light?
Green
226Are topical steroids recommended for epithelial injuries?
No, they delay epithelial healing
227What is a corneal foreign body?
An external object lodged on or within the cornea
228What is the usual history of corneal foreign bodies?
Trauma involving an object striking the eye
229What test detects aqueous leakage after corneal injury?
Seidel test
230What does a positive Seidel test indicate?
Aqueous humor leaking through a corneal wound
231What is the first step before corneal foreign body removal?
Topical anesthesia
232What is used to remove a superficial corneal foreign body?
Wetted cotton applicator
233What may be used to remove an embedded corneal foreign body?
Fine needle tip
234What is dry eye disease also called?
Keratoconjunctivitis sicca
235What is the main mechanism of aqueous-deficient dry eye?
Reduced tear production due to lacrimal gland dysfunction
236Which systemic disease is associated with dry eye and xerostomia?
Sjögren's syndrome
237Which autoimmune disease is associated with secondary Sjögren's syndrome?
Rheumatoid arthritis
238Which mucocutaneous conditions can reduce mucin secretion?
Stevens-Johnson syndrome and cicatricial pemphigoid
239What is meibomian gland dysfunction?
Abnormal function of the meibomian glands affecting the tear film lipid layer
240What is lagophthalmos?
Inability to completely close the eyelids
241What can cause lagophthalmos?
Facial nerve palsy
242What is the Schirmer test used for?
Measuring tear production
243What is a normal Schirmer test result according to the lecture?
More than 10 mm wetting in 5 minutes
244What is tear film break-up time (BUT) used for?
Assessing tear film stability
245What is a normal tear film break-up time?
More than 10 seconds
246What BUT result suggests dry eye?
Less than 10 seconds
247What does Rose Bengal stain?
Dead and devitalized ocular surface cells
248What color does Rose Bengal produce?
Pink
249What are the treatments for dry eye disease?
Tear substitutes, mucolytics, and punctal occlusion
250What mucolytic concentration is mentioned for dry eye?
Acetylcysteine 5%
251How can punctal occlusion be performed?
Temporary collagen plug or permanent cauterization
252What is the sclera?
Dense connective tissue forming the outer coat of the eye
253What portion of the globe is covered by the sclera?
Posterior five-sixths
254What is the main collagen type in the sclera?
Type I collagen
255Why does the sclera appear white?
Irregularly oriented collagen fibers
256Are corneal and scleral collagen continuous?
Yes
257What does the outer two-thirds of the sclera continue with at the optic disc?
Dura mater
258What does the inner one-third of the sclera join with?
Choroidal tissue to form the lamina cribrosa
259What passes through the lamina cribrosa?
Optic nerve fibers
260Which muscles insert into superficial scleral collagen?
Rectus muscles
261What is Tenon's capsule?
Anterior connective tissue covering the sclera and rectus muscles
262What does the bulbar conjunctiva cover?
Sclera and rectus muscles
263Where do Tenon's capsule and bulbar conjunctiva fuse?
Near the limbus
264Is the sclera generally vascular or avascular?
Generally avascular
265Where is the intrascleral vascular plexus located?
Posterior to the limbus
266Where is the superficial episcleral vascular plexus located?
Beneath Tenon's capsule
267What inflammation involves the superficial episcleral plexus?
Episcleritis
268Where is the deeper episcleral vascular plexus located?
On the scleral surface
269What inflammation involves the deeper vascular plexus?
Scleritis
270What are scleral emissaria?
Apertures allowing passage of blood vessels and nerves through the sclera
271What passes through anterior emissaria?
Anterior ciliary arteries
272What passes through middle emissaria?
Vortex veins
273What is the clinical significance of middle emissaria?
Potential route for extraocular extension of choroidal melanoma
274What passes through posterior emissaria?
Short and long posterior ciliary vessels and nerves
275What is the clinical significance of posterior emissaria?
Weakness near the lamina cribrosa
276What are Axenfeld loops?
Loops formed by ciliary nerve branches posterior to the scleral limbus
277Where are Axenfeld loops commonly located?
Nasal and temporal limbus
278What are the four histological layers of the sclera from outer to inner?
Episclera, scleral stroma, lamina fusca, and endothelium
279What is the outermost layer of the sclera?
Episclera
280What composes the episclera?
Dense vascular connective tissue
281What supplies blood to the episclera?
Anterior ciliary arteries
282What is the main component of scleral stroma?
Collagen bundles, fibroblasts, proteoglycans, and glycoproteins
283What is another name for scleral stroma?
Substantia propria
284What is the characteristic appearance of scleral stroma?
Opaque, porcelain-white
285What is the lamina fusca?
Pigmented inner layer of the sclera
286What structures blend with the lamina fusca?
Suprachoroidal and supraciliary lamellae
287What is the innermost basal lining of the sclera?
Endothelium
288What are the three main functions of the sclera?
Maintains globe shape, resists forces, and anchors extraocular muscles
289What is the thinnest region of the sclera?
Posterior to rectus muscle insertion
290What is the thickness of the thinnest scleral region?
0.3 mm
291What is the thickest region of the sclera?
Posterior pole around the optic nerve head
292What is the thickness of the posterior sclera?
Approximately 1.0 mm
293What is the scleral thickness at the equator?
0.4–0.5 mm
294What is the scleral thickness anterior to muscle insertion?
0.6 mm
295Why is scleral thickness important during surgery?
Prevents inadvertent penetration of the retina during suturing
296What is scleral melanocytosis?
Congenital benign melanocytic hyperpigmentation of the sclera
297What is the characteristic appearance of scleral melanocytosis?
Small black or gray-blue scleral spots
298What causes scleral melanocytosis?
Increased melanocytes in the iris, choroid, and surrounding structures
299What is oculodermal melanocytosis also called?
Nevus of Ota
300What characterizes nevus of Ota?
Scleral melanocytosis with facial skin hyperpigmentation