QuizWise 11

1. Which of the following is false about retinal vein occlusion (RVO)  in glaucoma
   a. The prevalence of glaucoma is higher in patients with RVO than in the general population
   b. History of glaucoma in the fellow eye is significantly more common in patients with RVO than in general population
   c. Glaucomatous eyes developing unilateral RVO may show faster progression compared to glaucomatous eye without RVO 
   d. None of the above. 

2. Which of the following is not a classical risk factor for development of retinal vein occlusion
   a. Smoking
   b. Hypertension 
   c. Diabetes mellitus 
   d. Hyperlipidaemia

3. Which of the following is seen in association with Branch retinal vein occlusion
   a. Glaucoma 
   b. Optic disc pallor 
   c. Collateral vessels 
   d. Retinal neovascularisation
   e. Retinal detachment and vitreous haemorrhage
   f. All of the above 

4. Which is not a haematological cause of retinal vein occlusion 
   a. Protein C and S deficiency 
   b. Antithrombin 3 deficiency
   c. Factor V leiden mutation 
   d. Protein C and protein S excess 

5. Which of the following statements about the natural history of Branch retinal vein occlusion is true
   a. The prognosis in terms of visual acuity depends on the presenting visual acuity 
   b. The majority of patients presents with a visual acuity of 6/36 or worse 
   c. The majority of patients experience significant visual improvement
   d. A minority of patients develop macular edema over the course of a year 

QuizWise 11 responses

1. Answer – d : None of the above. 

The prevalence of glaucoma is much higher in patients with RVO than in the general population. Studies have reported that a history of glaucoma in the fellow eye is significantly more common in patients with RVO than in controls. It has been hypothesised that elevated IOP may compress blood vessels and induce subsequent intimal proliferation, leading to collapse of retinal vessel walls. Optic disc cupping may distort retinal vessels at the disc, and this could predispose the veins to occlude. However, branched RVO (BRVO) has also been reported in eyes with normal-tension glaucoma, suggesting that risk factors other than IOP may contribute to the development of BRVO in eyes with glaucoma. 

Reference – Park HY, Jeon S, Lee MY, Park CK. Glaucoma progression in the unaffected fellow eye of glaucoma patients who developed unilateral branch retinal vein occlusion. American journal of ophthalmology. 2017 Mar 1;175:194-200.  DOI – 10.1016/j.ajo.2016.10.009 

2. Answer – a : Smoking 

There are interesting studies attributing a group of “classic” risk factors as more strongly correlated with the development of BRVO than CRVO, especially in patients younger than 50 years. Classic risk factors include hypertension, hyperlipidemia, and diabetes mellitus. 

Reference – Jaulim A, Ahmed B, Khanam T, Chatziralli IP. Branch retinal vein occlusion: epidemiology, pathogenesis, risk factors, clinical features, diagnosis, and complications. An update of the literature. Retina. 2013 May 1;33(5):901-10. doi: 10.1097/IAE.0b013e3182870c15

3. Answer – f : All of the above

Cystoid macular edema is a common sight-threatening complication of branch retinal vein occlusion (BRVO). Although BRVO and macular edema can resolve spontaneously within a year, prolonged hypoxia associated with the edema can result in irreversible reduction of visual acuity. A common cause for reduced visual acuity, secondary to chronic macular edema, is vitreous haemorrhage caused by new vessel formation. Increased VEGF levels will stimulate neovascularisation. Furthermore, retinal neovascularisation may lead to vitreous traction and retinal tears. Evidence of extrafoveal vitreous traction and vitreous traction at the occlusion site can be also found in cases of BRVO. Chronic BRVO would be more subtle and characterised by the appearance of venous collateral formation and vascular sheathing. 

Reference – Jaulim A, Ahmed B, Khanam T, Chatziralli IP. Branch retinal vein occlusion: epidemiology, pathogenesis, risk factors, clinical features, diagnosis, and complications. An update of the literature. Retina. 2013 May 1;33(5):901-10. doi: 10.1097/IAE.0b013e3182870c15

4. Answer – d : Protein C and protein S excess

Thrombophilla may be caused by deficiency of any of the regulatory factors required to avoid spontaneous spot formation. Protein C and protein S degrade activated factors 5 and 7 and therefore a deficiency in either may lead to a thrombophillic state.  Factor 5 leiden is a mutant factor resistant to inactivated by activated protein C and S.

Reference – 

5. Answer – d : A minority of patients develop macular edema over the course of a year 

The prognosis in terms of visual acuity in Branch retinal vein occlusion does not depend on the presenting vision. A systematic review of 24 studies on BRVO revealed that the presenting vision was found  to be 6/12 or worse. Upto 15%of patients developed macular edema over the course of a year. Upto 50% of untreated patients fail to show any form of significant visual impairment. 20% showed deterioration in their vision. 

Reference – Wong TY, Scott IU. Retinal-vein occlusion. New England Journal of Medicine. 2010 Nov 25;363(22):2135-44.DOI: 10.1056/NEJMcp1003934