Rhegmatogenous retinal detachment
This is defined as the presence of a hole or break in the retina that allows fluid from the vitreous capacity to enter the subretinal space. It usually occurs spontaneously in those who have a predisposition to it following trauma to the eye or after intra-ocular surgery. Most of these patients develop symptoms. A break in the peripheral retina is associated with a sudden burst of flashing lights or sparks that may be followed by small floaters or spots in the field of vision. When the retina detaches, the patient perceives a dark curtain progressing across the visual field, and when the fovea detaches central vision is abruptly diminished.It is treated surgically with a scleral buckling procedure (where all retinal breaks are localized and adhesions between the choroid and retina are performed around the break with diathermy or a cryoprobe). After draining the subretinal fluid, the detached portion of the retina is indented towards the vitreous cavity by a scleral implant or explant. This results in pushing of the retina towards the vitreous, causing closure of the retinal break (by the buckled sclera and choroid) and release of traction of vitreous.
Traction retinal detachment
The intact retina is forcibly elevated by contracting membranes on the surface of the retina or by vitreous traction on areas of retinal neovascularization. Causes include diabetes, intraocular foreign body, perforating eye injuries and loss of vitreous fol-lowing cataract surgery. These retinal detachments are difficult to treat; pars plana vitrectomy is the only way to treat these lesions.
Secondary retinal detachments
These occur secondary to systemic disorders including hypertension, toxaemia of pregnancy, chronic glomerulonephritis, retinal venous occlusive disease and retinal vasculitis. Treatment is directed towards the underlying cause as these detachments are not amenable to scleral buckling surgery.