Selecting a pair of sunglasses

Sunglasses may help you look cool and fashionable but they are also designed to protect your eyes, so choosing a pair of sunglasses is about more than just looking good.

1) The lenses

UV protection
It’s important to protect against excessive exposure to ultraviolet (UV) rays.

Make sure that you check to see if they protect against 99% of UVA rays and at least 95% of UVB rays.

If they are labeled as ‘cosmetic’ or don’t provide any information about UV protection, it’s better not to get them.

Distortion
Make sure you check for distortion by holding the lenses up to a fluorescent lamp. As you move the sunglasses up and down, check that there is no wave distortion that will also distort your vision. If there is none, this is a good sign.

Scratch resistance
Finally, make sure that the lenses in the sunglasses are scratch resistant, as scratched sunglasses are damaged and useless.

The colour
Note that the colour of the lenses doesn’t just affect your fashion statement, it affects how well you detect contrast and differentiate colours. The colour of the lenses you choose can make a difference to your vision and can enhance contrast, which is always useful, but the colour of the lens can also affect the ability of the eye to detect colour differences, which may be a problem – when driving, for example.

2) The frame

Shape
Sunglasses come in all shapes and sizes. Generally, finding a contrast between the shape of your face and the shape of the frame will look good. For example, if you have a round face, more angular frames will work well, and if your face is squarer, a rounder softer frame shape will look good.

Fit
Like any pair of glasses, choose sunglasses that fit your face and are comfortable to wear, so take care when trying on new pairs. They should feel well balanced and not squeeze the head, ears or nose, and sit on the bridge of the nose without touching the eyelashes.

The sunglasses should balance on the bridge of the nose and ears; if they feel inclined to one side, you need to adjust them.

The size
Make sure that the lens area is not too small, so that it will be able to block sunlight effectively

Retinal Vein Occlusion

This week’s blog on Retinal Vein Occlusion has been contributed by Dr Hassan Aziz, Consultant Vitreoretinal Surgeon.

What is Retinal Vein Occlusion?

Retinal Vein Occlusion occurs when a retinal vessel is occluded, blocking the drainage of the blood from the retina. This results in the accumulation of blood (retinal hemorrhages) and fluid (macular edema) in the retina and leads to a drop in the visual acuity (clarity of vision).

What are the risk factors for Retinal Vein Occlusion?

Risk factors for Retinal Vein Occlusion include: hypertension, diabetes mellitus, cardiovascular disease, primary open angle glaucoma.

What are the types of Retinal Vein Occlusion?

There are two types of Retinal Vein Occlusion:

  • Central Retinal Vein Occlusion (CRVO)
  • Branch Retinal Vein Occlusion (BRVO)

How is Retinal Vein Occlusion diagnosed?

Retinal Vein Occlusion is diagnosed clinically with a dilated eye examination. Additional imaging such as fluorescein angiography and ocular coherence tomography (OCT) may be needed to confirm the diagnosis and monitor the progression of the disease.

Treatment:

Treatment of Retinal Vein Occlusion includes:
Ocular treatment:

  • Observation if only a small vein is involved and does not affect the macula (central part of the vision).
  • Intravitreal injections of either anti-vascular endothelial growth factor (anti-VEGF) agents or steroid injection to treat the macular edema.
  • Laser photocoagulation may be administered to the peripheral ischemic retina.

Systemic treatment:

  • Management of systemic factors (close control of blood pressure and blood sugar levels).

Prognosis:

Retinal Vein Occlusions tend to have a relatively good prognosis if diagnosed and treated early. Delayed treatment may result in permanent retinal ischemia, neovascular glaucoma and tractional retinal detachment.