Ophthalmology Dr Sabin Sahu Consultant Ophthalmologist & Oculoplastic Surgeon "POS" Dr Sabin Sahu 1
• Class 1 : Cataract and lens disorders "POS" Dr Sabin Sahu • Class 2: Eyelid disorders • Class 3: Lacrimal and orbital disorders • Class 4: Conjunctival and Scleral disorders • Class 8: Trauma and ocular emergencies • Class 7: Uveitis and Retinal disorders • Class 6: Glaucoma • Class 5: Corneal ds “Practical Ophthalmology Series” 2
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Glaucoma "POS" Dr Sabin Sahu Relevant anatomy and physiology Glaucoma: Pathophysiology, Classification Diagnosis of glaucoma: IOP, Disc, Gonioscopy, VF Clinical types of glaucoma and managements Glaucoma management approach How to interpret a Visual field print? 1 2 3 4 5 6 4
Brief Anatomy and Physiology "POS" Dr Sabin Sahu 5
Aqueous production • Secretion: Non-pigmented epithelium of pars plicata (ciliary body). Functional unit - ciliary processes • Mechanism of aqueous production 1. Active secretion – 70% (Na+ K + ATPase and Cl – channels) 2. Ultrafiltration – 20% 3. Diffusion – 10% "POS" Dr Sabin Sahu 6
Drainage of aqueous humour 1. Trabecular outflow (Conventional) • IOP dependent route • 70-90% • Increases with age • Trabecular meshwork (TM) – Uveoscleral – innermost – Corneaoscleral – middle – Juxtacanalicular – outermost 2. Uveoscleral outflow (Unconventional) • IOP independent route • 10-30% • Decreases with age • Suprachoroidal space: – Space between ciliary body and sclera "POS" Dr Sabin Sahu 7
Aqueous outflow system "POS" Dr Sabin Sahu 8
Glaucoma • Definition – Glaucoma is a group of disorders characterized by chronic progressive optic neuropathy resulting in ▪ Characteristic optic disc change (due to retinal ganglion cell death) ▪ Irreversible, progressive visual field changes ▪ Associated frequently but not always with raised IOP (Raised IOP is a major Risk Factor) "POS" Dr Sabin Sahu 9
Pathophysiology of glaucoma • Mechanical theory (Intraocular pressure related events) Raised IOP → narrowing of openings in lamina cribrosa →reduced axoplasmic flow → glaucomatous optic atrophy and visual field defects • Ischemic theory (Intraocular pressure independent events) Structural changes in blood vessels supplying optic nerve → decreased optic nerve head perfusion → glaucomatous optic atrophy and visual field defects "POS" Dr Sabin Sahu 10
Classification of glaucoma I. Congenital/developmental glaucoma 1. Primary congenital glaucoma (without associated anomalies) 2. Secondary congenital / Developmental glaucoma • Peter anomaly • Axenfeld-Rieger anomaly • Sturge-Weber syndrome • Aniridia "POS" Dr Sabin Sahu 11
II. Primary glaucoma 1. Primary open-angle glaucoma (POAG) 2. Primary angle-closure glaucoma (PACG) 3. Primary mixed mechanism glaucoma "POS" Dr Sabin Sahu III. Secondary glaucoma 1. Lens induced glaucoma 2. Trauma induced glaucoma 3. Uveitic glaucoma 4. Steroid induced glaucoma 5. Neovascular glaucoma 12
Diagnosis of glaucoma • No single test to diagnose glaucoma ; involves several factors 1. Intraocular pressure measurement 2. Examination of angle of anterior chamber 3. Optic disc examination 4. Visual field examination "POS" Dr Sabin Sahu 13
1. Intraocular pressure measurement : Tonometry • Normal IOP = 11-21 mmHg • Diurnal variation: maximum in morning 8am12 noon. – Difference of 6 mmHg or more is significant in diurnal variation test. – Especially useful in evaluating Normal tension glaucoma "POS" Dr Sabin Sahu 14
Types of tonometry 1. Digital tonometry • palpation of eyes • Soft = low ; firm = normal; hard = high 2. Non-contact method • Pulsair / Air-puff tonometry - Choice for screening 3. Contact methods a. Indentation tonometry – Schiotz tonometer b. Applanation tonometry – Goldmann Applanation tonometer "POS" Dr Sabin Sahu 15
Schiotz tonometer • Parts: foot plate, plunger, additional weights • Always done in supine position • IOP is directly proportional to ocular rigidity • Nomogram conversion table is used "POS" Dr Sabin Sahu 16
Goldmann applanation tonometer • Imbert-Fick principle • Gold standard method • Steps: – Topical anesthesia – Fluorescein stain – Biprism brought in contact with cornea under cobalt blue light – Force adjusted until inner edges of mires just touch each other. – Multiply dial reading with 10 to get the IOP. "POS" Dr Sabin Sahu 17
Corrected IOP • Central corneal thickness adjusted. – Thicker cornea: falsely high IOP (True IOP will be lower than measured) – Thinner cornea: falsely low IOP (True IOP will be lower than measured) "POS" Dr Sabin Sahu 18
2. Examination of angle of AC • Done to classify glaucoma as open or closed angle • VanHerick’s method – ratio of peripheral anterior chamber depth (PACD) to corneal thickness (CT) ▪ PACD/CT ≥1 : Grade 4 – wide open ▪ PACD/CT <1/2 to >1/4: Grade 3 – mod. open ▪ PACD/CT ¼: Grade 2 – mod. narrow ▪ PACD/CT <1/4: Grade 1 – very narrow "POS" Dr Sabin Sahu 19
Oblique flashlight test • Light thrown from temporal side • Iris illuminated on both nasal and temporal side (No shadow): Angle is open (Deep AC) • Iris illuminated only in temporal side with shadow on nasal side (Eclipse sign): Angle closure (Shallow AC) "POS" Dr Sabin Sahu 20
Gonioscopy Principle: elimination of total internal reflection • Types of gonioscope: – Direct: Koeppe, Barkan, Swan-Jacob – Indirect: Zeiss four mirror, Posner four mirroe, Sussman four mirror "POS" Dr Sabin Sahu 21
1. Iris root 2. Ciliary body band (CBB) 3. Scleral spur (SS) 4. Trabecular meshwork (TM) 5. Schwalbe’s line (SL) (Mnemonic: I Can See The Stupid Line) Structures visible in angle on gonioscopy: "POS" Dr Sabin Sahu 22
Grading of angle width Shaffer’s system • Grade 0 = Iridocorneal contact, SL not visible • Grade I = only SL visible • Grade II = SL + TM visible • Grade III = SL + TM + SS visible • Grade IV = SL + TM + SS + CBB visible "POS" Dr Sabin Sahu 23
Slit lamp biomicroscopy + 90D lens Indirect ophthalmoscopy Direct ophthalmoscopy "POS" Dr Sabin Sahu 24 3. Optic disc examination
Right Eye "POS" Dr Sabin Sahu Left Eye • Disc lies nasal to macula! • During sit lamp examination with 90D, ask patient to look at your ears, the view will be focused on the disc! 25 Clinical pearl!
Optic disc • Size: Normal 1.5mm • Shape: circular or vertically oval • Color: pink color rim, cup looks white • Margin: sharp and distinct • Cup: central pale area of depression • Cup-disc ratio: normal 0.2-0.4 • NRR (neuroretinal rim): tissue between the cup-margin and the disc margin; Note its thickness, color, – ISNT rule: Inferior rim thickest, temporal rim thinnest • Peri-papillary Vessels : Retinal vessels ride up the nasal wall of the cup often with kinking at the cup margin. note any hemorrhages, neovascularisation "POS" Dr Sabin Sahu 26
Cup-Disc ratio (CDR) Cup-Disc ratio (CDR): • Normal = 0.2-0.4 • Glaucoma suspect: CDR > 0.5, OR Asymmetry of > 0.2 "POS" Dr Sabin Sahu 27
Cupping of the optic disc in compare to the normal optic disc "POS" Dr Sabin Sahu 28
Optic Disc Changes In Glaucoma A. Specific signs • Optic disc cupping: 1. Large optic cup (vertical CDR 0.7 or more) 2. Asymmetry of optic cup (difference of CDR 0.2 or more) 3. Progressive enlargement of optic cup 4. Does not obey the “ISNT” rule • Focal signs: 1. Notching of rim 2. Regional pallor 3. Splinter hemorrhage 4. Nerve fiber layer thinning B. Less specific signs: 1. “Lamellar dot” sign 2. Nasalization of vessels 3. Peripapillary crescent (Beta zone) 4. Barring of circumlinear vessels There are four cup signs, four focal signs and four less specific signs. "POS" Dr Sabin Sahu 29
Physiological Cupping 1. Optic disc: • No progression in cupping • Symmetrical cupping • Follows “ISNT” rule • Optic disc may be large • No focal changes or vessel abnormalities 2. Associated with consistently normal IOP and VF "POS" Dr Sabin Sahu 30
Few clinical signs of glaucomatous damage Disc hemorrhages: • Often extend from the NRR onto the retina, most commonly inferotemporally. • Their presence is a risk factor for the development and progression of glaucoma. • They are more common in Normal Tension Glaucoma. "POS" Dr Sabin Sahu 31
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Baring of circumlinear blood vessels: • It is a sign of early thinning of the NRR. • It is characterized by a space between the neuroretinal rim and a superficial blood vessel "POS" Dr Sabin Sahu 34
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Bayoneting sign: • It is characterized by double angulation of a blood vessel. • With NRR loss, a vessel entering the disk from the retina may angle sharply backwards into the disk and then turn towards its original direction to run across the lamina cribrosa "POS" Dr Sabin Sahu 36
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Collaterals: • Collaterals between two veins at the disc similar to those following central retinal vein occlusion (CRVO), are relatively uncommon. • They are probably caused by chronic lowgrade circulatory obstruction. Retinal vascular tortuosity may also occur. "POS" Dr Sabin Sahu 38
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• Loss of neuroretinal rim (NRR) – Hoyt’s sign – Early sign: loss of inferotemporal rim (polar notching) – Late sign: loss of nasal NRR, sharpened edge or rim "POS" Dr Sabin Sahu 40
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Bean pot cupping: • Eventual loss of all neural rim tissue results in total cupping which is characterized by white disc with bending of all vessels at disc margin "POS" Dr Sabin Sahu 42
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Laminar dot sign: • Occurs in advancing glaucoma. • Grey dot-like fenestrations in the lamina cribrosa become exposed as the NRR recedes. "POS" Dr Sabin Sahu 44
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Peripapillary changes: • Peripapillary atrophy (PPA) surrounding the optic nerve head may be of significance in glaucoma • may be a sign of early damage in patients with ocular hypertension. "POS" Dr Sabin Sahu 46
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Retinal nerve fibre layer defects: • Two patterns occur: (a) localized wedge-shaped defects and (b) diffuse defects that are larger and have indistinct borders. • Red-free (green) light increases the contrast between normal retina and defects and typically makes identification easier. "POS" Dr Sabin Sahu 48
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Red-free photograph of the same eye "POS" Dr Sabin Sahu 50