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PubMed1985

Funduscopic systems: magnification in ametropia and aphakia.

The magnification of the fundus image with various forms of funduscopy in ametropia and aphakia is poorly understood. This paper investigates these relationships. Direct and indirect ophthalmoscopy and biomicroscopic funduscopy is included. The Gullstrand Simplified Schematic Eye is modified by changing either the axial length, the power of the cornea, or the index of refraction of the lens to produce ametropia. Aphakia is produced by considering these same eyes with the crystalline lens removed. The magnification of these various eye/funduscope systems is presented, along with general principles illustrated by the figures.

Aphakia↗
PubMed1980

Contact lens versus intraocular lens in the correction of aphakia.

The insertion of an intraocular lens at the time of cataract surgery has become a very popular method of correcting aphakia. However, it is not done without adding extra risks to the operation and postoperative course. The use of a contact lens, though not quite as effective from a visual standpoint, involves fewer risks. The use of the extended-ear soft contact lens will further enable to correction of aphakia. The more the extended-wear lens becomes successful, the less need will there be for an intraocular lens.

Aphakia, Postcataract↗
PubMed1994

Epikeratophakia for correction of complicated aphakia.

We reviewed the cases of 21 patients (22 eyes) who underwent epikeratophakia for aphakia with at least 4 months' follow-up. Thirteen had traumatic cataracts, six had relative contraindications for implantation of an intraocular lens (IOL), one had a dislocated IOL and one had bilateral congenital cataracts. The mean best corrected visual acuity was 20/32.0 (range 20/20 to 20/70) before surgery and 20/38.6 (range 20/20 to 20/70) after surgery. The uncorrected visual acuity improved in all eyes. Twenty eyes (91%) were within two lines of the preoperative best corrected acuity; all eyes were within four lines. Twenty eyes were within 3.0 dioptres of emmetropia postoperatively; all eyes were within 5.0 dioptres of emmetropia. No serious complications were encountered. We conclude that epikeratophakia is a good alternative for the correction of aphakia.

Adolescent↗
PubMed1992

Results of intraocular lens implantation in paediatric aphakia.

Intraocular lenses were implanted in 16 eyes of 13 patients with congenital cataract, and visual progress was plotted using a preferential-looking technique. Initial surgery was by lens aspiration with preservation of the posterior capsule, and subsequent posterior capsulotomy without anterior vitrectomy. Poly-HEMA posterior chamber lenses were used, usually as a primary procedure but in four cases as a secondary procedure after contact lens failure. No serious complications were encountered. Most eyes achieved a very significant visual improvement, and none were worse than preoperatively. Residual refractive error was highly unpredictable, but did not exceed 6 dioptres. The importance of rigorous occlusion therapy is stressed. With close follow-up, this procedure offers an effective and safe method for the correction of unilateral paediatric aphakia, and, in selected cases only, for bilateral aphakia.

Cataract↗
PubMed1990

[The association of strabismus and aphakia in children].

The frequency and polarity of secondary strabismus was related retrospectively to the onset of deprivation in 131 children with mono- and bilateral aphakia after congenital cataract or perforating injury. The frequency was highest in patients up to 2 years of age at the onset of deprivation. From the 3rd year on, it declined to 50% or less. Esotropia was predominant in the first 2 years of life. At the end of the first decade of life exotropia was up to 80%.

Aphakia↗
PubMed1979

[Fusion and aniseikonic problems in unilateral aphakia (author's transl)].

In 67 unilateral aphakic patients corrected with three different optic systems (conventional contact lens, spheric overcorrection and intraocular lens) aniseikonia and binocular vision are tested. Conventional contact lens leads to 7% aniseikonia and to fusion in only half of the cases. Patients with the two other systems show less than 3% aniseikonia and fusion in most cases. With each system only 10% of the patients reach normal stereoscopic vision. The poor results in unilateral aphakia corrected by conventional contact lens are pointed out.

Adult↗
PubMed2005

Blood-aqueous barrier changes after the use of prostaglandin analogues in patients with pseudophakia and aphakia: a 6-month randomized trial.

OBJECTIVES: To investigate the effects of prostaglandin analogues on the blood-aqueous barrier and to evaluate the occurrence of cystoid macular edema in aphakic or pseudophakic patients with glaucoma. METHODS: In this randomized, masked-observer, 6-month clinical trial, patients with primary open-angle, pseudophakic, or aphakic glaucoma were treated once daily with bimatoprost (n = 16), latanoprost (n = 15), or travoprost (n = 17) or twice daily with unoprostone (n = 16) or lubricant drops (control group) (n = 16). Blood-aqueous barrier status, which was assessed using a laser flare meter; intraocular pressure; the occurrence of angiographic cystoid macular edema; and conjunctival hyperemia were evaluated. RESULTS: Mean flare values were significantly higher in the bimatoprost, latanoprost, and travoprost groups throughout follow-up (P < .02). Four latanoprost-treated eyes, 1 bimatoprost-treated eye, and 1 travoprost-treated eye developed cystoid macular edema; all cases resolved after discontinuation of the prostaglandin analogue and treatment with topical diclofenac sodium. Mean intraocular pressure reductions after 6 months were higher for the latanoprost (26%), bimatoprost (28%), and travoprost (29%) groups than for the control (3%) and unoprostone (14%) groups (P< .05). Bimatoprost induced significantly higher hyperemia scores than latanoprost, unoprostone, and placebo (P< .01). CONCLUSION: Bimatoprost, latanoprost, and travoprost use may lead to disruption of the blood-aqueous barrier in patients with pseudophakia and aphakia.

Aged↗
PubMed1982

Blood-retinal barrier in eyes with long-standing aphakia with apparently normal fundi.

Vitreous fluorophotometry was used to evaluate the integrity of the blood-retinal barrier in 130 eyes with long-standing aphakia and apparently normal fundi. All patients had undergone intracapsular lens extraction because of senile cataract and had been followed up for approximately one year (group 1) or three years (group 2). Thirty normal eyes served as controls. Thirty minutes or one hour after intravenous administration of fluorescein sodium, 50 of 130 aphakic eyes (32 of 70 group 1 eyes; 18 of 60 group 2 eyes) and three of 30 control eyes were judged abnormal in breakdown of the blood-retinal barrier. In aphakic eyes, the older the age at operation, the higher the incidence of barrier breakdown. These results indicate that the blood-retinal barrier remains disrupted for a longer postoperative period than was previously thought, and that the incidence of barrier breakdown relates to the age at operation. Although these findings reflect subclinical phenomena, they are biologically important.

Age Factors↗
PubMed1986

Epikeratophakia for pediatric aphakia.

We used epikeratophakia for rehabilitation in 11 contact lens-intolerant aphakic children aged 9 months to 14 years. Minimum follow-up was five months; the longest was 12 months. There were no graft failures, and no patients were unavailable for follow-up. Objective postoperative overrefractions on all patients revealed that an average of 93% of the desired correction was obtained. Residual corrections ranged from -3.75 diopters spherical equivalent to +2.87 D. Nine of the 11 children were of verbal age; their spectacle visual acuities averaged 20/50, with a range of 20/20 to 20/80. Preverbal children all tolerated occlusive therapy, although accurate visual acuities could not be obtained. Our early results with this modality as therapy for monocular aphakia in the pediatric population have demonstrated improvement in visual function in all patients to date.

Adolescent↗
PubMed2001

A double-deletion mutation in the Pitx3 gene causes arrested lens development in aphakia mice.

The recessive aphakia (ak) mouse mutant is characterized by bilateral microphthalmia due to a failure of lens morphogenesis. We fine-mapped the ak locus to the interval between D19Umi1 and D19Mit9, developed new polymorphic markers, and mapped candidate genes by construction of a BAC contig. The Pitx3 gene, known to be expressed in lens primordia, shows zero recombination with the ak mutation on our intersubspecific intercross panel representing 1170 meioses. A recent report described a deletion in the intergenic region between Gbf1 and Pitx3 as the possible ak mutation. Our results differ in that we find not only the distant intergenic deletion, but also a much larger deletion directly in the Pitx3 gene, eliminating exon 1 and extending into intron 1 and the promoter region. Pitx3 transcript levels are severely reduced in ak/ak mice from E11.5 to newborn (5 +/- 1% of the wildtype levels at E13.5), while an involvement of the flanking Gbf1 and Cig30 genes in the aberrant lens development is highly unlikely based on expression analysis. We conclude that the ak mutation consists of two deletions, the larger of which removes part of Pitx3, indicating a crucial role of this gene in early lens development.

Acetyltransferases↗
PubMed1979

Contrast (modulation) sensitivity functions measured in patients with high refractive error with emphasis on aphakia: I. Theoretical considerations.

Recently, alterations in contrast (modulation) sensitivity functions of patients with high refractive errors have been noted. For example, this seems to be a common finding in aphakia. In some measure the observed alterations are due to the effect of the corrective lens and the optics of the eyes. These optical effects (in addition to blur) must be factored out in order to determine whether residual effects on the visual system remain. The argument is applicable to photographs of sine wave fringes as well as devices designed to produce interference patterns directly on the retina. A simple means for largely correcting these lens effects is discussed.

Aphakia↗
PubMed1979

Contrast (modulation) sensitivity functions measured in patients with high refractive error with emphasis on aphakia: II. Determinations of patients.

Measurements of Constrast Sensitivity Functions (CSF) were made on normal observers made artificially highly ametropic with spectacle lenses (with high back vertex) distance in order to determine the effect of retinal image size alterations upon CSF measures. While not an exact model for high ametropia per se, this experiment served to familiarize the experimenters with problems associated with the task. Image size alterations occur normally in aphakic patients and highly myopic patients. As a clinical trial, a series of aphakic observers were tested using an interferometric acuity device. CSF measures were made with the patient's spectacle corrections in place and again with correcting contact lenses substituted. The contact lenses reduce induced image size alterations in these cases. The use of contact lenses in such measures allows differentiation between artifactual low frequency fall off in aphakia due to lens effects and possible low frequency fall-off due to other causes.

Adult↗
PubMed1977

[Unilateral aphakia in juveniles. Results of combined correction (author's transl)].

Eighty-one unilateral aphakies under 45 years of age, 63 of which had suffered an injury, were analyzed by echometry and intraocular optics. With the aid of a computer, the majority of cases were treated for restoration of nearly equal images in both eyes by combined correction, i.e., an appropriate spectacle -- contact lens combination with both distant and near vision in the aphakie eye taken into consideration. Results with unilateral post-traumatic aphakia (63 cases) : 31 patients with uncorrected vision and 42 with a conventional contact lens suffered from symptoms of binocular confusion as opposed to only one patient with combined correction. Of the 63 patients with uncorrected vision or with a conventional contact lens, 44 had strabismus. After optimal treatment with combined correction, with or without subsegment strabismus surgery, 19 out of 23 patients were cured of their strabismus and regained a useful and comfortable, distant and near binocular vision. Thus, for juvenile unilateral aphakics, a rather good prognosis was achieved by combined correction.

Adolescent↗
PubMed2002

[Retropupillary fixation of the iris claw lens in aphakia. 1 year outcome of a new implantation techniques].

INTRODUCTION: There are several surgical options available for the correction of aphakia. We investigated if retropupillary fixation of an iris claw lens is a method combining the advantages of posterior chamber implants with a new low-risk method of intervention. PATIENTS AND METHODS: An iris claw lens was implanted in 48 eyes in the plano-convex direction (model 205 Y). For the calculation of the IOL power we estimated an A-constant of 116.8. The lens was pushed via a 5-mm wide corneal incision vertically in the anterior chamber and was fixed in the retropupillary position after turning in the horizontal direction. After aspiration of the viscoelastica the corneal incision was closed by a 10-0 nylon suture. RESULTS: The implantation was successful in all patients. A visual improvement was noted in 27 patients (56.2%), an unchanged visual acuity was seen in 18 patients (37.5%) while 3 patients (6.2%) showed a loss of visual acuity. A cystoid macular edema was found by fluorescein angiography in two cases. Leakages in the area of the enclavation were not seen. SUMMARY: The retropupillary fixation of an iris claw lens seems to have the advantages of a true posterior chamber implantation with a low intra- and postoperative risk profile. The easy implantation process with this technique could replace the normally applied sclera suture fixed implantation of a posterior chamber lens as the method of choice.

Aphakia↗
PubMed1985

Localization of keratin in the cells of the cornea in aphakia and normal mouse embryos.

Abnormal lens morphogenesis in the aphakia mutant in the mouse often results in a club-shaped elongated 'lens' that remains attached to the surface epithelium by a persistent connecting stalk, which is partially solid and partially cystic. Usually, the cells are continuous with the surface epithelium of the cornea and also with the cuboidal cells lining the corneal inner surface. Immunofluorescence with keratin antiserum not only gave positive reactions with the corneal epithelial cells, but also with many cells of the lens stalk, including its cysts, and with islands of cells on the inside of the cornea. These keratin-containing 'endothelial' cells may be the product of metaplasia of the endothelium into epithelium-like cells. Alternatively, they may also be the result of abnormal migration of epithelial cells into the eye or of abnormal differentiation of neural crest cells.

Animals↗
PubMedDate not supplied

Elimination of aniseikonia in monocular aphakia with a contact lens-spectacle combination.

Correction of monocular aphakia with contact lenses generally results in aniseikonia in the range of 7--9%; with correction by intraocular lenses, aniseikonia is approximately 2%. We present a new method of correcting aniseikonia in monocular aphakics using a contact lens-spectacle combination. A formula is derived wherein the contact lens is deliberately overcorrected; this overcorrection is then neutralized by the appropriate spectacle lens, to be worn over the contact lens. Calculated results with this system over a wide range of possible situations consistently results in an aniseikonia of 0.1%.

Aniseikonia↗
PubMed1986

Automated refraction in aphakia--II. Its repeatability and accuracy compared to conventional techniques.

The repeatability and accuracy of an i.r. electronic optometer (the Ophthalmetron) and of retinoscopy performed by experienced practitioners were studied in aphakia by testing a group of 17 patients three times with each method and by subjective techniques. The results show that the Ophthalmetron gives better repeatability than retinoscopy and that accuracy is marginally better for the sphere with the Ophthalmetron and for the cylinder power by retinoscopy when the mean of the three subjective results is taken as the true refractive value.

Adult↗