Retinal detachment – congenital, primary, secondary.
Retinal detachment is a condition where there is separation of the two retinal layers, the retina proper and the pigmentary epithelium by the sub retinal fluid.
Classification:
Based on the clinical etiology, renal detachment can be classified into the following types:
- Congenital
- Primary
- Secondary
2. Primary or simple (rhegmatogenous) retinal detachment
This is the most frequent from of retinal detachment which results from a tear i.e. break in the retina. This break in the retina forms a hole through which sub-retinal fluid seeps and separates the sensory retina from the pigmentary retina. Usually this break occurs in the peripheral retina and rarely in the macula. Two types of breaks may occur: a round break (this is when a portion of the retina has been completely torn out due to a posterior vitreous detachment) and a horse-shoe tear (when the retina is only slightly torn).
Note that not every retinal break leads to retinal detachment. This will occur only where the liquefied vitreous body separates, and vitreous humor penetrates beneath the retina through the tear. The retinal detachment occurs when the forces of adhesion can no longer withstand this process.
Etiology: The etiology is unclear; however, here are a few predisposing factors.
i) Age (40-60 year olds commonly) ii) Sex (more common in males) iii) Myopia (40% of primary retinal detachment cases are myopic) iv) Aphakia – this is the absence of the lens of the eye due to surgical removal, a perforating wound or ulcer or a congenital anomaly v) Trauma
Clinical features:
- Prodromal symptoms which include dark spots (floaters) in front of the eye (due to rapid vitreous degeneration) and photopsia (due to irritation of retina by vitreous movements).
- Sudden painless loss of vision
- On examination, the external eye is usually normal, intraocular pressure is usually slightly lower or maybe normal.
- On ophthalmoscopy, the freshly-detached retina gives grey reflex instead of normal pink reflex and is raised anteriorly.
Treatment: Sealing of retinal breaks – the retinal breaks are localized and sealed by producing aseptic chorioretinitis, with cryocoagulation. Subretinal fluid drainage may be done to allow immediate apposition between the sensory retina and the retinal pigment epithelium.
- Secondary retinal detachment: this occurs secondary to ocular diseases or pathology. It can either be tractional or exudative.