Suspect it clinically, if one notices highly attenuated arterioles, thinned & atrophic looking retina, asymmetric appearing DR (actually not asymmetric as revealed on FFA- which must be done in any doubt). Tip-306...... Carotid occlusive disease causing Ocular ischemic syndrome can present as eye or browache & deteriorating vision. TIAs & amaurosis attacks may occur. Fundus may show retinal arteriolar narrowing, venous dilatation, micros, retinal hemorrhages, soft exudates, neovascularisation & even arteriolar pulsations. Patients commonly suffer from heart attack (IHD) or brain stroke (CVA). Treatment is anti-platelet therapy & Carotid endarterectomy. Tip-307....... Few facts about ROP .... -Think of Aggressive ROP (AROP), if pupil is not dilating. -Indications for ROP screening in India is: birth weight of </= 2000 grams or Gestational age of </= 34 weeks (Internationally it is 1500 grams & 30 weeks).
-Anti-VEGF in ROP (see Tip-131) is considered in Zone-1 ROP, non-dilating pupil & hazy media. FDA has approved Lucentis for ROP in 2019. Tip-308...... Artificial Intelligence (AI) in retinal imaging: Machine Learning (ML) rather than manual analysis filters relevant information from 'Big data'. It detects 'morphological fingerprints' e.g. predicting whether individual patient with drusen has higher risk for developing CNVM. Another example is to detect intra/subretinal fluid on OCT scan on different antiVEGFs treatments by Deep Learning (DL is superior subset of ML). Tip-309...... IRVAN syndrome (Idiopathic Retinal Vasculitis, Aneurysms & Neuroretinitis, 1995): -Rare, bilateral, inflammatory, idiopathic (autoimmune?) syndrome. -Multiple macroaneurysms (knotted/beaded arteries) are the hallmark. -Unlike Eales', (age group similar), vascular sheathing is uncommon, macroaneurysms (>50 mn, microaneurysms are 10-50 mn
sized) in first order arterioles and exudates are common, but treatment is almost similar. Tip-310....... Few important facts about Ocular Tuberculosis (OTB) Also see Tip-167: 1. Most commonly manifests as Tubercular uveitis (TBU), more specifically Tubercular choroiditis (TBC). Different phenotypes exist e.g. Serpiginous like choroiditis (SLC, See Tip-180), Multifocal choroiditis, Focal choroiditis, Tubercular retinal vasculitis (TRV) with perivascular sheathing (same as Eales'). 2. Diagnosis of OTB is mostly presumed, as no single pathognomonic lesion or immunological test is confirmatory. Direct detection of Mycobacterium (only confirmatory test) in tissues is mostly not practical or feasible & has poor yield. 3. Latent TB (no active TB infection) gives positive immunological tests (Mx & IGRA) & PCR, hence strong clinically suspicious lesion is must before starting ATT. 4. No international agreement exists on therapeutic regime & duration of treatment. COTS (Collaborative ocular TB study) is trying to standardize these in collaboration with IUSG & IOIS.
Tip-311..... Reason & remedy for poor fundus image (FI) on fundus camera: 1. Small FI- long working distance between lens of camera and eye. Go closer. 2. White spot in top of FI- lens is too close. Take it away. 3. Dark shadow in top of FI- Lens is slightly lower than the visual axis. 4. Dark shadow in the bottom of FI- Lens is slightly higher than the visual axis. 5. Blue or white flare at the edge of FIAngle of lens needs to be adjusted to avoid corneal reflections. Tip-312....... OCT in general is not meant for peripheral retina; however peripheral retinal imaging is possible with OCT by1. Steered image capture. Heidelberg Spectralis has steerable laser head. 2. Montaging the images. However, both are time consuming (need 20-30 minutes) & significantly reduce the resolution. 3. Optos (Silverstone model)- is full-field Swept-source OCT capturing peripheral retina (beyond vortex ampulla) in single scan (23mm line scan possible, 1mm~5*). For advantages of peripheral OCT, follow Tip-313.
Tip-313...... Some applications of peripheral OCT (i.e. imaging anterior to vortex ampulla): 1. Extent of retinal breaks, detachment & schisis can be exactly delineated. 2. Retinal Tuft commonly misdiagnosed as retinal hole on clinical examination becomes easily differentiable. 3. Small subclinical retinal fluid around lattice degeneration is easily picked up. 4. Vitreo-retinal adhesions or traction around lattice can be easily defined. 5. Masquerades such as retinoschisis and retinal detachment are easily differentiable. 6. Tele-ophthalmology would allow it to be interpreted by remotely placed retinologist. Tip-314...... Cobblestone (Paving stone) degeneration is peripheral chorioretinal degeneration seen as multiple, depigmented, well defined, atrophic punched out areas mainly in inferior retina & is usually an incidental finding requiring no treatment. Tip-315..... Many recent studies have demonstrated 2 times increase in rate of diabetic retinopathy (DR) detection with UWF fundus camera (100-200° of retinal imaging) & have shown that peripheral NPDR lesions are associated
with 4 times increased risk of disease progression in next 4 years. Tip-316...... Many Non-mydriatic digital fundus cameras (NMFC) are now available including those from India (Remidio & Forus). Advantages of NMFC include: 1. saves time of dilatation. 2. Eliminates need for bright lights & flash making it comfortable for patient. 3. No fear of precipitating acute ACG attack at the remote place during community screening. 4. Some are also portable, telemedicine compatible & have artificial Intelligence (AI). 5. Useful for community outreach programs and screenings in glaucoma, DR & AMD. Locally trained personnel can click the picture & send for interpretation by remotely placed ophthalmologist. Tip-317....... Postoperative choroidal detachment is usually self limiting and resolves within days to two weeks, if the cause (hypotony and inflammation) is removed. Cycloplegics and steroids help.
Tip-318....... Retinoblastoma can occasionally occur in older children (above 5 years of age) commonly masquerading as inflammatory disease (uveitis/endophthalmitis), but it remains painless and without congestion. Many of these are of diffuse infiltrating type. Tip-319...... Choriocapillaris are better studied on Sweptsource OCTA and not on ICGA, which visualises the larger choroidal vessels better. Loss of choriocapillaris (as in AMD) deprives nutrition to RPE and outer retina causing ischemia with greater likelihood of drusen and CNVM. Tip-320..... To be safer, if Anti-VEGF is injected as vitrectomy adjunct for fibrovascular proliferation in TRD, surgery must be performed within 4 days of injection; since rapid involution of fibrovascular proliferation can lead to progression of TRD. Tip-321.... Fancy sign described on SD-OCT is the 'Flying saucer sign' in HCQ (Hydroxy chloroquine) toxicity, in which there is loss
of hyper-reflective Ellipsoid layer in perifoveal area but thickening of underlying RPE-Bruch's complex. Tip-322..... No Stem cell treatment for any retinal disease (e.g. ARMD, Retinitis pigmentosa, Stargardt) is FDA approved till today & at best be considered experimental. Greatest potential risk in stem cell treatment anywhere in the body is that changing the nuclear structure of cell can lead it to multiply uncontrolled and cause cancer. Tip-323....... As per COTS group recommendations, among many Tubercular uveitis (TBU) phenotypes (see Tip-310), Serpiginous like choroiditis (SLC) & Tuberculoma are highly suggestive of tubercular etiology. Hence, consider starting the ATT even if one immunological test (Mx or IGRA) is positive. Add systemic steroids if no systemic infection exists. By contrast, Multifocal or Focal choroiditis are less likely to be of tubercular etiology & require both immunological & radiological tests to be positive before starting ATT.
Tip-324...... Feeder vessel photocoagulation (only of feeding arteriole & Never of vein) is now no more recommended for sea-fan neovascularisation (e.g. in Eales', Sickle cell disease); rather Scatter laser is done surrounding the sea-fan. Tip-325...... Optociliary shunt (Retinochoroidal shunt) vessels are not the shunt (arteriovenous communications bypassing capillary network) vessels in literal sense, but are actually the 'collaterals' formed on the optic nerve head (e.g. in CRVO) and join retinal venous circulation with peripapillary choroidal veins. Collaterals are always formed from dilatation of pre-existing capillary network. Tip-326..... Before undertaking cataract surgery, always remember the rare possibility of posterior capsular tear in any patient who has received the Intravitreal injection. Especially suspect, if there are linear opacities in lens or the cataract has progressed rapidly. If doubtful, treat it like posterior polar cataract i.e. avoiding hydrodissection & doing optic capture of IOL.
Tip-327..... Intravitreal injection if planned during cataract surgery, is best injected after the IOL is implanted but before the viscoelastic removal. Tip-328...... Large submacular (subretinal) hemorrhage (SMH) most commonly occurs due to Polypoidal choroidal vasculopathy (PCV) besides CNVM & RAM (Retinal arterial macro aneurysm). Subretinal hemorrhage is more & faster damaging to photoreceptors than sub-RPE hemorrhage. Subretinal hge is bright red unlike darker blood in sub-RPE. For treatment of SMH, follow Tip-329. Tip-329...... Treatment of Submacular hemorrhage (SMH): Mono or combined therapy as follows1. Anti-VEGF injection alone if SMH is small. 2. Pneumatic displacement by expansile gas with anti-VEGF & with/without rTPA (recombinant TPA). Patient lies face down for 3-5 days.
Tip-330.... Intraretinal fluid (IRF) is more damaging to retinal structures & has worse visual acuity than subretinal fluid (SRF) IRF responds (especially if naive/untreated before) better to Anti-VEGF than SRF. Small refractory SRF may be left, if the vision is stable (no need to dry it completely). IRF is either Degenerative (smaller & more square shaped & is due to disintegrated RPE & neural elements) or Exudative (larger more active exudation & more oval & responds better to anti-VEGF Tip-331...... Anterior vitrectomy tips after posterior capsular rent (PCR) during Phaco for anterior segment surgeons....... Primary aims are to clear the vitreous from AC (without pulling/traction on vitreous (base) & to avoid enlarging PCR. Use closed chamber technique (keep AC always formed) with 2 side ports. Lower the bottle height. Keep low vacuum & flow rate but highest cutting rate (that machine allows, reduces traction). Infusion cannula tip is kept close to port but away from PCR.
Vitrectomy cutter tip is kept just under the PCR. Tip-332...... Upto 50% of patients of diabetic macular edema (DME) may not respond or become refractory to anti-VEGF treatment (no BCVA or CMT improvement). Cause is supposed to be mitochondrial oxidative damage (apoptosis). Flavoprotein fluorescence (FPF) is the new biomarker test for mitochondrial function, this is checked by Ocumet Beacon device (from Ocusciences, Michigan, USA). Oxidised FPF indicates mitochondrial dysfunction. Thus unlike OCT, it acts as functional test (Retinal metabolic analysis) and not structural. Tip-333..... For detecting metallic RIOFB, always order the CT scan with 1mm (or sub-mm) sections through the globe so as not to miss the foreign body. Tip-334....... On OCT scan, Central retinal/macular thickness (CRT/CMT) measures the mean retinal thickness within 1mm diameter circular field surrounding the fovea, while
Central foveal thickness (CFT) or Centre point thickness measures the retinal thickness at the intersection of 6 radial scan lines. Tip-335...... Patients with Cone dystrophy are highly photosensitive & they benefit from tinted glasses especially orange or red coloured, because rods' sensitivity is less to orange and red lights. Photosensitivity is actually due to poor visual acuity in bright lights and not real intolerance to light Tip-336..... Drusen are the hallmark of AMD, but presence of drusen in old people doesn't always mean AMD, as hard drusen (see Tip62) (especially if scanty, scattered or nonconfluent) can occur in aging retina without developing any significant AMD changes like soft drusen and CNVM throughout the life. Aging retina and AMD is a spectrum and no definite demarcation line exists between the two. Tip-337....... Intraoperative OCT (iOCT) for real time scans during vitreo-macular interface surgeries is now being increasingly used, as
it provides detailed intraoperative anatomical views which are not possible with microscope (difficult visualisation of transparent structures without dye). It provides real time, high resolution visualisation of all the surgical maneuvers e.g. whether ERM removal is complete, any full thickness break introduced during the surgery, etc. Tip-338..... 'Double-layer sign' on SD-OCT scan was first described in Polypoidal choroidal vasculopathy (PCV), but has now been shown in AMD, chronic CSCR, high myopia and other Pachychoroid diseases also. There is irregular and shallow PED with two separate hyper-reflective bands on OCT: upper of RPE & lower one is of Bruch's i.e. separation of RPE & Bruch's. Tip-339...... PCR testing (detects DNA) in general is considered more specific than serological testing (e.g. ELISA for IgG/M). Hence in Ocular Toxoplasmosis, PCR testing in aqueous or vitreous samples is more specific and reliable than ELISA.
Tip-340..... Hyper-reflective dots (HRD)/Spots/Foci are an SD-OCT finding in many retinal diseases (DME, AMD, Vascular occlusions, CSCR, Commotio retinae, etc.). It could be of inflammatory or non-inflammatory (microglial cells having phagocytosed outer segments of photoreceptors) origin. Unlike hard exudates, it can occur in any of the retinal layers & cause no shadowing. HRDs are generally considered an ominous sign & the bad OCT biomarker. (Also see Tips- 78 & 207). Tip-341.... There is no definite treatment known for serous or drusenoid pigment epithelial detachments (PEDs). For Hemorrhagic or fibrovascular PEDs, Anti-VEGF injection, PDT or retinal laser (if extrafoveal) is required. Serous PEDs in CSC resolve in majority or may leave behind the pigment mottling. Extrafoveal PEDs don't affect the vision unlike subfoveal ones. Drusenoid PEDs have the best prognosis, while hemorrhagic or fibrovascular PEDs have the worst. Large PEDs on anti-VEGF injection may develop RPE Rip (see Tip-200).
Tip-342...... Ocriplasmin (Jetrea) by ThromboGenics/Oxurion Inc.: FDA approved (2012) for Intravitreal injection for symptomatic vitreo-macular adhesion (VMA) (seeTip-85). Is modified human Plasmin enzyme. Cost ~4000 USD (marketed by Novartis). Production discontinued since 2020. Was available as 0.5mg/2ml injection. Diluted to 0.4ml & finally 0.125 mg is injected as one time injection. Resolves VMA in ~25%. Tip-343...... Broadly among the congenital retinal dystrophies, in general, Retinitis pigmentosa, Leber congenital amaurosis (LCA) & Cone-rod dystrophies are progressive; while CSNB & Monochromatism are stationary. Tip-344...... None of the Ultra-wide field fundus cameras (including Optos Daytona) can take ora to ora fundus photo in one click. Optos provides the largest field of view (FOV) of 200° (80% of fundus in one field). Zeiss Claris/130° FOV, Spectralis/102° FOV & Mirante/160° FOV (Nidek) provide
the true colour perception & higher image resolution. Spectralis (both contact & non-contact options are available for USF imaging) makes closer contact with patient even with non-contact option. Retcam (CMS, USA) also uses contact lens, hence cumbersome. Tip-345..... Vitamin-A supplements should be avoided in ABCA4 associated retinopathies (e.g. Stargardt's disease). ABCA4 gene (located on chromosome -1) is responsible for the production of protein that cleans up the substance which damages the photoreceptors (actually by A2E , the bisretinoid chemical that gets excessively produced). Approximately 50% of all autosomal recessive cases of Cone-rod dystrophies are related to ABCA4 gene mutations (making it defective). Stargardt's patients should also be asked to quit smoking. Tip-346…... Patients of ARMD, DR, RP or even Optic neuritis, Ocular migraine & Vertebro-basilar ischemia can also complain of flashes of light or photopsiae besides classically mentioned for PVD & RD. These are the
Phosphenes (visual hallucinations induced without any external light). Patients describe it as flashes, moving stars, different shapes of colours which are floating or shimmering or zigzagging. Phosphenes may sometimes occur even in normal eyes & can be induced by rubbing, pressing or moving the eyeballs. Phosphenes occur due to direct or indirect stimulation of photoreceptors or neurons in LGB or visual cortex. Tip-347...... Intravitreal injection of Pegcetacoplan (Syfovre by Apellis Co.) has been approved by FDA (in Feb'23) for Geographic atrophy (advanced form of dry AMD). There was no approved treatment for Geographic atrophy so far. Pegcetacoplan (15 mg in 0.1 ml injection) is a localised complement C3 inhibitor of immune system. May be commercially available in Mar'23. Tip-348...... In future, measuring choroidal thickness (by SS-OCT) in myopia might be used as predictive biomarker for eyeball elongation and thus myopia progression. Choroidal thickness and axial length are probably inversely related. Decreased choroidal blood
flow causes choroidal thinning & scleral architectural changes with elongation of eyeball and induction of progressive and pathological myopia. Tip-349...... Choroidal circulation (supports RPE & outer retinal metabolism) impairment with changes in choroidal thickness is implicated in the pathogenesis of hosts of retinal disorders: ARMD, PCV, CSR, Myopic chorioretinal atrophy, etc. EDI-OCT & Swept source OCT are used to measure choroidal thickness. SS-OCT instrument acquires a choroidal thickness map using a fully automated choroidal segmentation algorithm with good reliability and reproducibility. No standard international protocol is available for measuring choroidal thickness by OCT. Tip-350..... Definition of Wide field imaging (50-100°) for all fundus imaging modalities (fundus photo, FFA, FAF, OCT, OCTA) is that it should capture all four retinal quadrants including posterior edge of vortex ampulla, while Ultra wide field imaging (UWF) captures beyond anterior edge of vortex ampulla in all 4 quadrants (100-200°).
Machines for UWF OCT (See Tips- 312 & 313) are: -Heidelberg Spectralis HRA-OCT -Silverstone (Optos) -Mirante (Nidek) -Plex Elite 9000 (Zeiss) -Xephilio OCT-S1 (Canon). ---THE END ---