Optical Intraocular lenses

Iso 11979-2. Ophthalmic Implants—Intraocular Lens—Part 2 Optical Properties and Their Test Methods. Switzerland (1999). 

Saika et al. (79) reported on a group of 19 eyes that had pars plana vitrectomy, elevation of the posterior hyaloid, fluid gas exchange, and cataract extraction with intraocular lens implant. Ten of the 19 eyes had decreased in macular edema as identified on optical coherence tomography the mean thickness decreased from 383 to 208 pm. However, there was no statistically significant improvement in visual acuity. If only patients with more recent onset of branch retinal vein occlusion were included in the analysis, a visual improvement was noted. 

Hammer ME, Burch TG. Viscous corneal protection by sodium hyaluronate, chondroitin sulfate, and methylcellulose. Invest Ophthalmol Vis Sci 1984 25 1329-1332 Harrison SE, Soil DB, Shayegan M. Clinch T. Chondroitin sulfate a new and effective protective agent for intraocular lens insertion. Ophthalmology 1982 89 1254-1260 Hayreh SS. Anterior ischemic optic neuropathy. Occurrence after cataract extraction. Arch Ophthalmol 1980 98 1410-1416... 

Werner L, Apple DJ, Kaskaloglu M, Pandey SK. Dense opacification of the optical component of a hy(i ophilic acrylic intraocular lens a... 

Note OADRs = ocular adverse drug reactions CV = color vision VF = visual field VL = vision loss NFL = nerve fiber layer lOP = intraocular pressure NSAIDs = nonsteroidal anti-inflammatory drugs TBUT = tear break-up time CL = contact lens IH = intracranial hypertension RD = retinal detachment NAION = nonarteritic ischemic optic neuropathy. 

The eye is a complex sensory organ, which receives visual information from the environment. It encodes optical information into complex electrical signals, which are transmitted to the cortex for visual imagery through the optical nerve. The visual efficiency primarily depends on the optical clarity of the eye (e.g., cornea, crystalline lens, and intraocular media) and the neural integrity of the visual pathway (e.g., retina, optic nerve, and visual cortex). 

Pseudoexfoliation syndrome is a degenerative systemic disorder that is primarily characterized by deposits of distinct fibrillar material on the surfaces lining the anterior and posterior chambers of the eye, although these are most easily visualized on the lens capsule. The disease is often associated with cataract and severe high-intraocular pressure glaucoma that result in rapid deterioration of the optic nerve. 

With an ageing population, the occurrence of cataract has increased. This disease results in opacification of the natural crystalline lens. The only way to treat this kind of blindness is to extract the opacified lens and to replace it either externally by very thick glasses, or internally by intraocular lenses (lOLs). PMMA that has been modified by the addition of an ultraviolet-filtering additive to protect the retina has been used to manufacture the optic part of the device. 

We had occasion to extend the concept to the development of materials for potential use in intraocular lenses [45]. Appropriately shaped dry resin lenses were to be surgically implanted. Upon exposure to the fluids in the eye, the polymer was to swell and assume the correct optical shape for proper vision. This concept required that the polymer should take up at least 409/o of its weight as water to produce a swollen polymer that had a refractive index of no less that 1,40 to permit the proper optical corrections to be applied to the lens. Assuming that refractive indices of mixtures or solutions are additive, this requires a polymer with a refractive index about 1.5 so that 40 70 of water with nn 1.33 will result in a hydrogel in the desired... 

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