Corneal oxygen uptake under a soft contact lens in phakic and aphakic eyes.
(73/91)
A simple and comfortable procedure is used to measure the decay of oxygen content of a soft contact lens on a human cornea when the anterior surface of the lens is blocked from further supply of oxygen. Calculations from this measurement give the steady-state oxygen tension under the soft contact lens and the oxygen flux into the cornea when the eye is open but wearing a contact lens. When the procedure is applied to phakic and aphakic human eyes, the results indicate that for both states, the oxygen uptake by the cornea is about the same when the uptake levels are above 1 microliter/cm2 . hr and oxygen tensions under the lens are above 10 mm Hg. (+info)
Extended-wear aphakic soft contact lenses and corneal ulcers.
(74/91)
A review of 100 aphakic extended-wear soft contact lenses is presented for the period July 1980 to August 1981. Four previously successfully fitted patients with either American Optical Company's Sofcon or Cooper Laboratories' Permalens for extended wear developed corneal ulcers either directly under the lenses or shortly after removal. Three of the female patients were well controlled diabetics without retinopathy, one of whom sustained severe visual loss and neovascular glaucoma after a pseudomonas ulcer. Another patient, who had developed a Seratia marcescens ulcer 3 months later, developed metastatic carcinoma of the bowel. Special attention to diabetic aphakic patients being fitted with extended-wear soft contact lenses is suggested. (+info)
Follow-up of aphakic patients with anterior vitrectomy in one eye and uneventful cataract extraction in the fellow eye.
(75/91)
Twenty patients had operations for bilateral cataract in 2 separate sessions, with uncomplicated extraction on one side and vitreous loss managed with anterior vitrectomy on the other. The cataracts, the type of surgery, and the postoperative treatment were identical in both eyes. The differences between the 2 eyes were not statistically significant so far as the amount of astigmatism, final visual acuity, and peripheral anterior synechiae were concerned. The main difference was found to be the period of time the vitrectomised eyes remained red and uncomfortable as compared to the eyes with uncomplicated surgery. (+info)
Corneal swelling response of the aphakic eye.
(76/91)
Corneal swelling response was measured for 12 unilateral aphakic subjects wearing high-plus hydrogel contact lenses on both eyes. Significantly less corneal edema was measured for aphakic eyes than for phakic eyes after 2, 4, and 6 hr of lens wear. These results indicate that the cornea of the aphakic eye responds differently to a given physiologic challenge than does the cornea of the phakic eye. Previous estimates of oxygen permeability required of contact lens materials for extended wear may be artificially high for aphakic eyes. (+info)
Acute aphakic pupil block glaucoma: an alternative surgical approach.
(77/91)
In a series of 7 cases of acute aphakic pupil block glaucoma a surgical approach designed to break adhesions between the iris and the anterior hyaloid face was uniformly successful. Reasons for the success of the method are discussed and comparisons made with other surgical approaches. (+info)
Development of grating acuity in children treated for unilateral or bilateral congenital cataract.
(78/91)
PURPOSE: To study the development of grating acuity in children treated for dense congenital unilateral or bilateral cataract and to examine how variations in treatment affect grating acuity during early childhood. METHODS: The authors used optokinetic nystagmus (OKN), preferential looking (PL), or both to measure the grating acuity of children treated for congenital cataract in one eye (n = 63) or both eyes (n = 77) whenever possible from the time of treatment until 3 years of age. At each age, the authors compared patients' monocular acuity to that of children with no history of eye disorders. RESULTS: The OKN acuity of treated eyes did not improve with age and was abnormal by 12 months of age. In contrast, PL acuity improved with age, and acuity of most treated eyes was not outside normal limits until 24 to 30 months of age. Nonetheless, at 12 months and at 3 years of age, PL acuity correlated significantly with age at treatment in children who had bilateral cataract. In children who had unilateral cataract, PL acuity correlated significantly with the number of hours per day the good eye had been patched since treatment. Children whose good eye was patched fewer than 3 hours per day did significantly worse than children treated at a comparable age for bilateral congenital cataract. However, children whose good eye was patched at least 3 hours per day had PL acuities similar to those of children treated at a comparable age for bilateral congenital cataract. CONCLUSIONS: Children treated for congenital cataract show deficits in grating acuity, with the deficit apparent earlier in OKN acuity than in PL acuity. At least by 1 year of age, visual development has begun to be influenced by the age at treatment and, in children treated for unilateral cataract, by patching of the good eye. (+info)
The purpose of this study was to determine the corneal epithelial alterations induced by various types of contact lenses. By employing the specular microscope, the corneal epithelia of 60 patients who had worn contact lenses for more than 1 year were re-examined along with 15 myopic controls. The morphological changes in aphakic patients who changed from extended wear soft to extended wear rigid gas permeable lenses were also studied. The mean cell area of the corneal epithelium was 621.5 (SD 92.5) microns 2 for daily wear rigid gas permeable lenses (n = 15), 645.8 (98.1) microns 2 for daily wear soft lenses (n = 15), and 634.7 (88.6) microns 2 for extended wear rigid gas permeable lenses (n = 15), none of which differed significantly from the control value of 610.5 (98.1) microns 2. Only the extended wear soft lens group (n = 15) showed significantly enlarged epithelia (806.1 (50.1) microns 2, p < 0.01 versus the other groups). The epithelium partially returned to normal after changing from extended wear soft lenses to extended wear rigid gas permeable ones. The corneal epithelium showed increased cell area only with extended wear soft contact lenses which are known to pose a risk for corneal infection. (+info)
Neonatal lensectomy and intraocular lens implantation: effects in rhesus monkeys.
(80/91)
PURPOSE: To compare the effects of a lensectomy with and without intraocular lens (IOL) implantation on a neonatal rhesus monkey eye. METHODS: A lensectomy and anterior vitrectomy was performed on 75 monkeys during the first 16 days of life; 21 of these monkeys also had an IOL implanted into the posterior chamber. The eyes were examined at regular intervals using biomicroscopy, applanation tonometry, and ophthalmoscopy. RESULTS: The pseudophakic monkeys were studied until they were 92.5 +/- 5.8 weeks of age and the aphakic monkeys until they were 80.4 +/- 5.7 weeks of age. Pupillary membranes (100% versus 55.5%; P < 0.01) and lens regeneration into the pupillary aperture (28.6% versus 5.6%; P = 0.02) occurred more often in the pseudophakic than the aphakic eyes. As a result, the pseudophakic eyes required more reoperations than the aphakic eyes to keep the visual axis clear (P < 0.01). There was not a significant difference in the incidence of ocular hypertension between the pseudophakic and aphakic eyes (9.5% versus 12.7%; P = 0.34). Pupillary capture of the IOL optic occurred in 52% and haptic breakage in 33% of the pseudophakic eyes. All of the eyes with broken haptics had a prominent Soemmerring's ring varying in maximum thickness from 0.6 to 2 mm. Nine of the haptics from the seven eyes with broken IOLs had eroded into the iris, two into the ciliary body, and one into the anterior chamber. CONCLUSIONS: Implanting an IOL into a neonatal monkey eye after a lensectomy and anterior vitrectomy increases the likelihood of a reoperation being necessary. Haptics frequently erode into the iris and ciliary body and may break because of stress placed on the optic-haptic junction by forward movement of the IOL. (+info)