Effect on the retina of an air cushion in the anterior chamber and coaxial illumination.
In an attempt to minimize the danger of light-induced maculopathy during cataract surgery with intraocular lens implantation, we assessed the refractive power of a posterior chamber lens inserted with its convex surface forward (Procedure 1) and with its plano surface placed forward (Procedure 2). In both procedures, a large air bubble is placed in the anterior chamber while the corneoscleral wound is being sutured. With the convex surface forward, parallel rays of light focus 23.6 mm behind the intraocular lens and 5 mm behind the retina. For a pupil 5 mm wide, the diameter of the beam on the retina is 1.03 mm; for a pupil 2 mm wide, the beam is 0.41 mm wide. With the plano surface forward, the refracting surface is in contact with water and its power is therefore reduced. Parallel rays of light focus 97.3 mm behind the intraocular lens and 79.6 mm behind the retina. For a pupil 5 mm wide, the diameter of the beam on the retina is 4.14 mm; for a pupil 2 mm wide, the beam is 1.66 mm wide. Thus, the intensity of the radiation experienced by the retina per surface unit is only 6.19% of that produced when the convex surface is forward.
D000388:Air; D000867:Anterior Chamber; D006801:Humans; D007910:Lenses, Intraocular; D008027:Light; D008722:Methods; D012029:Refraction, Ocular; D012542:Scattering, Radiation