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PubMedDate not supplied

[The first results of the contact lens correction of aphakia in young infants].

Soft contact lenses (SCL) were used for the correction of aphakia in young children. Eleven surgeries were carried out in 7 children with congenital cataracts (aspiration in 2 cases and transciliary lensectomy in the rest). SCLs were made individually of gel with 70% water content by mechanical treatment, their parameters differing from the commercial 'aphakic' lenses. These SCL parameters were chosen with consideration for the data of measurements of the corneal curvature and diameter, carried out during surgery and then specified by trials. To determine the optic force of SCL, a special formula and skiascopy were used. Only in one case the parents refused from SCL application, being satisfied with the cosmetic effect of surgery; in the rest cases SCLs were tolerated satisfactorily as evidenced by a follow-up of 3 to 8 months. SCL wearing improved the visual function, that manifested in a more stable fixation, reduction and stabilization of strabismus angle, development of an ability to recognise closely situated small articles. These results are in fact tentative; further studies will be aimed at a more accurate assessment of the visual function and of the corneal status (including the status of the endothelium).

Aphakia, Postcataract↗
PubMedDate not supplied

[The role of early contact lens correction in the rehabilitation of nursing infants with aphakia].

The authors analyze the results of early (on days 5-8 postoperation) contact correction with soft contact lenses (SCL), carried out in 126 infants (206 eyes), operated on for congenital cataract extraction at the age of 2-12 mos. Soviet IOZM, Czechoslovak Spofa-lens, and American Bausch and Lomb lenses have been applied for 18-14 hrs daily, in parallel with the treatment for amblyopia (direct occlusion, a total exposure of the retina), carried out at home. A thorough adaptation, observance of the hygiene and schedule of the lens use have been a guarantee of the absence of ocular complications. SCLs considerably improve the vision acuity and are recommended for early correction of aphakia after congenital cataract extraction, carried out during the first months of infant life.

Aphakia, Postcataract↗
PubMedDate not supplied

[The interaction of the coloboma and aphakia mutant genes in mice].

The eye development has been studied in the 12-day-old, 14-day-old embryos and in neonates of Cm/+ ak/ak genotype. The gene coloboma (Cm) in heterozygous state causes a typical coloboma of the iris and the gene aphakia (ak) blocks the lens development in the homozygotes. It has been shown that in Cm/+ ak/ak mice the eyes go through mainly the same abnormal development as that in +/+ ak/ak animals. In mice of both genotypes the lens morphogenesis blocking at the vesicle stage and the retinal fold in the dorsal half of the eye develops. However, the ventral retinal fold which is characteristic for the +/+ ak/ak mice does not form in the Cm/+ ak/ak animals that is the result of the interaction of Cm and ak genes in the eye morphogenesis. The Cm gene suppressing the growth of the retina ventral half inhibits the formation of its fold in Cm/+ ak/ak embryos. As a result of the gene interaction a certain normalization of the eye development compared to the +/+ ak/ak mice is observed in the Cm/+ ak/ak animals. The obtained data show that the Cm gene expresses in the cell clones of the retina ventral half.

Animals↗
PubMed1977

Contact lens in aphakia.

Aphakia may be said to be the best reason for contact lenses. All types are used--(hard) corneal lenses, soft lenses both for daily and extended wear, and even (hard) scleral lenses in exce,tional cases. At present all have their problems so that, although on theoretical grounds an extended wear lens would be ideal, the corneal lens is probably still the lens of choice.

Aphakia, Postcataract↗
PubMed1977

The theoretical ideal for an artificial lens implant to correct aphakia.

In considering the theoretical ideal for an artificial intraocular lens implant to be used in the correction of aphakia it has always been taken for granted that Nature's bioconvex lens is best. But there is some evidence that other configurations may be an improvement. We also have to decide how large it should be and whether it should be placed in front of the iris or behind it. Moreover we have to consider the management of eyes which are already aphakic when first seen and cataractous eyes requiring lens extraction before the pseudophakos can be inserted.

Aphakia↗
PubMedDate not supplied

[Secondary implantation of the anterior-chamber intraocular lenses with flexible supportive elements for correction of aphakia].

The authors have designed an anterior-chamber intraocular lens (IOL) with flexible supporting elements and examined the possibility of its application for secondary correction of aphakia. Secondary implantations of such IOLs have been performed in 25 eyes. The implantation has proved to be low-traumatic and effective: the vision acuity has been unchanged or improved in 92% of cases, the loss of endothelial cells has made up 8.5% when the Healon bioprotector has been used and 10.3% without it. Criteria have been developed for the selection of patients for secondary implantation of IOL.

Adult↗
PubMed1989

Development of acuity in a primate model of human infantile unilateral aphakia.

We are studying infant rhesus monkeys that have been reared under various conditions of deprivation to model infantile unilateral aphakia. Grating acuity was assessed in these monkeys from birth to approximately 1 year of age using the quick acuity card procedure. We found that an uncorrected aphakic eye develops little or no pattern vision. Undercorrection or near point optical correction of an aphakic eye with an extended-wear contact lens coupled with continuous occlusion of the opposite eye sometimes results in normal development of acuity in the aphakic eye but does so only at the cost of loss of vision in the occluded eye. Fifty percent partial occlusion coupled with near-point correction of the aphakic eye results in similar development of acuity for both eyes during the time tested. Monkeys wearing near-point correction in the aphakic eye and without any occlusion of the other eye show surprisingly good residual acuities in their aphakic eyes. Based on these results we conclude that aphakic eyes should be treated by providing them with an optical correction, and that occlusion of the opposite eye should be used cautiously.

Animals↗
PubMedDate not supplied

[Prognostication of results in correction of aphakia by lamellar refractive keratoplasty].

The authors analyze the possibility of predicting the results of aphakia correction by interlamellar refraction keratoplasty from one of the eye parameters measured before surgery, the anterior corneal surface radius. The prognosis efficacy has improved by 10% vs. the prediction from the mean value; this is insufficient for practical application of the method. The prediction may be made more accurate if the number of the eye parameters measured before surgery is increased and the measurements are more precise.

Algorithms↗
PubMed1989

[Comparison of the status of binocular function in corrected mononuclear aphakia and pseudophakia].

The authors investigated in a group of 31 adults with unilateral aphakia the state of binocular functions and evaluated the differences between a group of patients corrected with contact lenses and a group with pseudophakia. The investigation revealed surprising (excellent) results as regards the restoration of satisfactory binocular vision in particular in pseudophakias (85%), somewhat poorer results with contact lenses (72%) which is favourable for the return of patients into practical life.

Aphakia, Postcataract↗
PubMedDate not supplied

The anterior eye segment in virus induced primary congenital aphakia.

Nine aphakic eyes from human embryos infected with Rubella or Parvovirus B19 during early pregnancy were histologically examined. One of the eyes conformed with the classical description of primary congenital aphakia (PCA), namely, that no structures of the anterior eye segment are present. However, the other eight eyes did reveal such structures. In these eyes embryological development and differentiation of the anterior eye segment had taken place, despite the fact that no lens had formed previously. On the basis of this study it is concluded that PCA is not necessarily associated with aplasia of the anterior eye segment.

Anterior Eye Segment↗
PubMed1987

Circling keratorraphy: a new approach to surgical correction of aphakia (preliminary communication).

A new approach to surgical correction of hyperopia (including aphakia) is advanced. A ring-shaped inlay of biologically-inert polymer is imbedded into the cornea in order to make its curvature steeper. The corneal tissue is displaced centripetally by constant traction around its optical zone. No corneal grafting or incision in the optical zone is required. The simplest way to carry out the procedure is to place a buried intracorneal suture in a circle 6 to 8 mm in diameter. The suture must be tied strongly enough to ensure sufficient bulging of the cornea inside the circle. Then it will remain buried inside the cornea permanently. The term "circling keratorraphy" was coined for the technique. The results of the first six procedures performed on patients are presented and are considered to be promising. Some improvements in the exactness and delicacy of the technique are required; this work is currently in progress.

Aphakia, Postcataract↗
PubMed1978

[On the correction of posttraumatic unilateral aphakia in children and in adults with artificial intraocular lens implants (author's transl)].

The problems of optical correction of unilateral traumatic aphakia are discussed. The treatment of choice is a combined Cataract-operation with intraocular lens implants. The operation must be done as soon as the eye is free of inflammation. Prescription of bifocal glasses in addition to pseudophakoi is necessary. With this method a "malignant" Strabismus can be avoided and binocular vision, stereopsis as well as minimal grade of aniseikonia can be achieved.

Adolescent↗
PubMedDate not supplied

[Mutant gene expression in murine aggregation chimeras. 7. The effect of the aphakia gene--disorder in the formation of the crystalline capsule].

An analysis of aphakia (ak) gene expression in 16 day ak/ak C/C----+/+ c/c chimaeric embryos has shown, that ak gene, acting in developing lens, blocks lens cell differentiation and disturbs the formation by these cells of the extracellular matrix composing the lens capsule material. The dependence of capsule structure in chimaeras on the genotype of underlying cells indicates that lens cells are responsible for the formation of lens capsule.

Animals↗
PubMed1985

Refractive surgery for aphakia and myopia.

Epikeratophakia is a simple and reversible form of refractive surgery for the correction of aphakia and myopia and for the treatment of keratoconus, perforation and pterygium. The tissue lenses are attached to the de-epithelialised cornea; no invasion of the central optical zone is required. The safety of this procedure makes it a potential solution to the problem of optical correction in infants and children with congenital and traumatic cataracts. With the advent of commercially prepared tissue lenses, this surgery should become accessible to many ophthalmic surgeons. In the future, the combination of epikeratophakia and alloplastic lenses may provide high plus powers and exchangeable dioptric corrections, if a plastic can be found that the cornea will tolerate on a long-term basis.

Adult↗
PubMedDate not supplied

[Expression of mutant genes in mouse aggregation chimeras. 4. The aphakia gene].

Analysis of aphakia (ak) gene expression in ak/ak C/C in equilibrium +/+ c/c experimental chimaeras has shown that the ak gene acts in the lens rudiment cells blocking it differentiation. In the lens of 12 day old ak/ak C/C in equilibrium +/+ c/c chimaeric embryos undifferentiated ak/ak cells were present among the normally differentiating fibres. In 14 and 18 day old chimaeric embryos and 20 day old chimaeric mice ak/ak cells are located under the lens epithelium and the capsule of posterior lens half. In the locations of ak/ak cells on the posterior lens surface capsule breaks resulted in the extrusion of lens material into the secondary eye cavity. In all studied chimaeric embryos the lens structure is more similar to that in the normal embryos, than in ak/ak embryos. This suggests that in the developing chimaeric lens ak/ak cells are sorted out as the development proceeds. The proliferation rate of +/+ cells appears to be higher than that of ak/ak cells.

Animals↗
PubMed1979

An extended wear hard contact lens in aphakia.

In reviewing the literature, there are several reports of limited success with both hard and soft contact lenses for continuous or extended wear. Aphakia is the most common indication for continuous wear, especially in monocular aphakes who are unable to insert and remove their lenses for various reasons. Because of its unusual oxygen permeability, silicone is the logical choice of material for an extended wear lens. However, because of the problems in manufacture, as well as its hydrophobic characteristics, poor centering, and problems with proper edging, no silicone lens has had wide clinical application to date. This paper reports on a preliminary study in a group of 21 aphakic patients fitted with the Polycon lens made of a new material consisting of polymethylmethacrylate in combination with silicone. Although gas permeable, the oxygen permeability is probably not adequate to maintain corneal metabolism without some interchange of oxygen containing tears. However, a significant proportion of the patients were able to wear this lens for an extended period of time without removal.

Aged↗