Zero or low-power IOL implantation rather than planned aphakia.
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We retrospectively studied secondary intraocular lens (IOL) implantation in 165 aphakic patients (162 eyes) from May 1983 to August 1989. Seventy-five eyes (46.3%) had secondary IOL implantation; these included seven cases of trans-sulcus scleral fixation of the posterior chamber lens. The remaining 87 eyes could not have secondary IOL implantation because of the ocular conditions. The most common reason for secondary implantation was to relieve the discomfort caused by spectacles or contact lenses (56.2%). An anterior chamber lens was used in 43 eyes (57.3%) and a posterior chamber lens in 32 eyes (42.7%). Final postoperative visual acuity of 20/40 or better was achieved in 92.0% of the eyes with posterior chamber lenses, in 71.4% of the eyes with anterior chamber lenses, and in 57.1% of the eyes with scleral-fixated posterior chamber lenses. Endothelial cell loss was greater in the eyes with anterior chamber lenses than in the eyes with posterior chamber lenses. Of the cases that could be followed, 83.3% showed endothelial cell loss of less than 30% at six months postoperatively. Postoperative complications such as cystoid macular edema, persistent fibrinous membrane formation, and neovascular glaucoma occurred in only ten (13.3%) of the 75 eyes that had secondary implantation. These complications occurred more frequently in eyes that had anterior chamber lenses with anterior vitrectomy. There were no noticeable complications in the eyes that had trans-sulcus scleral fixation of posterior chamber lenses. Updrawn pupil, prolapsed vitreous, and peripheral anterior synechia were common conditions preventing secondary IOL implantation.
Following extracapsular senile cataract extraction, visual thresholds were measured in 15 aphakic eyes corrected with glasses and compared with an appropriately matched group of 23 eyes with poly (methyl methacrylate) posterior chamber lenses. All subjects were six months to three years postoperative and had 20/30 or better visual acuity. The paramacular dark adapted threshold, the foveal luminance threshold, and the glare effect on both thresholds were not significantly different in the two groups despite the optical differences between aphakic and pseudophakic correction.
The effects of glare on contrast sensitivity and high contrast Snellen acuity were investigated in a group of unilaterally aphakic patients with normal fellow eyes. In spite of relatively good visual acuity and apparently satisfactory surgical results, there was a marked reduction in contrast sensitivity in epikeratophakia and contact lens corrected aphakic eyes, relative to fellow normal eyes, especially in the presence of glare (P less than 0.05). Although the results from the pseudophakic patients were more variable, there is some evidence to suggest that epikeratophakia provides inferior visual function to contact lens correction or intraocular lens implantation. The results also suggest that the measurement of visual acuity in the presence of glare fails to identify many patients with a functional visual impairment secondary to glare.
Diffractive bifocal contact lenses function by diverting incident light to two focal points. Light from near objects is focused by diffraction while that from distant objects is focused by conventional refraction. Both processes occur simultaneously throughout the full aperture of the lens. Fourteen aphakic and pseudophakic contact lens wearers were fitted with diffractive bifocal lenses and observed for an eight week period. Six (42.8%) were satisfied with the visual result. Five subjects (35.7%) discontinued lens wear complaining of poor quality of near vision. We conclude that these lenses may help selected aphakic patients to discard their reading glasses but the low acceptance rate suggests that this type of optic is probably not suitable for implantation as an intraocular lens.
The fusion amplitude of image pairs with aniseikonia was measured using the synoptophore. Aniseikonia was produced in five subjects by alteration of slide drawings. The subject's right eye was in cycloplegia after paralysis with cycloplegic eye drops. To compare these measurements with aniseikonic pictures to those using the same image pairs without aniseikonia the fusion amplitude achieved was expressed as a percentage of the aniseikonia-free fusion amplitude. The relation between aniseikonia, eccentricity of the image borders and percent fusion amplitude was described using a mathematical approach. The experimental results reveal that a minimal increase in overall aniseikonia with greater eccentricities (greater than 5 degrees) leads to a rapid decrease in the fusion amplitude and the occurrence of diplopia. The aniseikonia tolerance level of images with greater eccentricities achieved experimentally and theoretically are in good agreement with results found in unilaterally aphakic patients.
Permalens contact lenses for extended wear offer further possibilities for correcting aphakic eyes. In some cases they may constitute an alternative to intraocular lenses. Preliminary results of a long-term study are presented.
Prostaglandin analogs are powerful ocular hypotensive agents that may also be associated with a breakdown of the blood-retinal barrier and cystoid macular edema. The association is evident in pseudophakic or aphakic patients. This paper presents a case of unilateral latanoprost-associated clinical cystoid macular edema in a bilaterally pseudophakic patient; the only difference between the two eyes was the presence of a capsulotomy in the affected eye. We review the literature concerning prostaglandin analog-associated cystoid macular edema, as well as the evidence for prostaglandin analog-associated breakdown of the blood-retinal barrier. Although some evidence is suggestive of a connection between prostaglandin analogs and cystoid macular edema, many questions concerning the complex physiology of prostanoids remain. Until our understanding of these issues is more advanced, judicious use of prostaglandin analogs in patients at risk for cystoid macular edema would be prudent.
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