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PubMed1990

Corneal topography of patients with excellent Snellen visual acuity after epikeratophakia for aphakia.

A computer-based corneal topographic analysis system was used to evaluate the patterns of power distribution in five patients with at least six months of postoperative follow-up who obtained excellent visual and refractive results after epikeratophakia for aphakia. All grafts were well centered relative to the visual axis. The range of surface power seen within the central 5 mm of the individual grafts ranged from 4.00 to 6.50 diopters. Each graft showed a unique, moderately irregular pattern of power distribution. Fair correlation was seen between the expected corneal power and that shown in the power map displays. These data suggest that moderate degrees of irregular astigmatism are compatible with good Snellen visual acuity after epikeratophakia for aphakia, though the effect of this irregularity on visual performance remains unclear.

Aged↗
PubMed1987

The nationwide study of epikeratophakia for aphakia in children.

In the nationwide study of epikeratophakia, 97 surgeons performed a total of 335 procedures in 314 eyes for the correction of aphakia in children under the age of 8 years 1 month. Fifteen children underwent bilateral surgery. Thirty-six tissue lenses were removed and 21 of these eyes underwent a second epikeratophakia procedure. Overall, the success rate for procedures was 89%, and with repeated surgery it was 95% for eyes. Seventy-three percent of the patients were within 3 diopters of emmetropia after surgery. Visual acuity results in patients able to provide verbal responses to the illiterate E, Allen card, or Snellen line chart testing showed improvement in most cases. The safety of epikeratophakia makes it a desirable option for the correction of aphakia in children who are spectacle or contact-lens intolerant, and the permanence of the correction eliminates the problem of optical noncompliance.

Aphakia↗
PubMed1979

Hard contact lens corrections in aphakia.

Hard contact lens correction of aphakia is best performed with a single cut lens by a trial lens fitting. Lenticular design may be necessary. Continuous wear over age 70 may be necessary to achieve success and acceptance in more than 30% of aphakic wearers. Soft lenses are usually not practical in the author's experience. The increased use of intraocular lenses is decreasing the need for aphakic contact lenses. Merits of the hard contact lens in aphakia are discussed as a practical approach to the correction of vision by the ophthalmologist, and indications for single cut lenses and lenticular design are outlined.

Age Factors↗
PubMed1986

Extended-wear contact lens correction of aphakia in infant primates. Corneal studies.

Extended-wear contact lenses (EWCL) are being used increasingly for the correction of aphakia in infants, but there is a lack of data documenting their effects on the corneas of young children. Therefore, corneal studies were performed on infant monkeys wearing EWCL for the correction of surgical aphakia. Nine newborn monkeys underwent unilateral lensectomy and anterior vitrectomy. Seven eyes were fitted with aphakic EWCL postoperatively and two wore no lenses. After at least six months, corneas were studied with slit-lamp and specular microscopy, and with light microscopy (LM) and electron microscopy (EM). Small central corneal opacities developed in two aphakic eyes corrected with EWCL after episodes of keratoconjunctivitis. One of these corneas was found to have a mildly increased coefficient of variation (CV) of endothelial cell size (polymegathism). Although EWCL are well tolerated by the corneas of aphakic infant primates, their association with endothelial polymegathism, which may indicate physiologic compromise, mandates careful long-term follow-up.

Animals↗
PubMed1987

Synthetic keratophakia for the correction of aphakia.

Although the majority of aphakic patients will have intraocular lens implants (IOLs), there are several groups of patients for whom IOLs are not indicated. Synthetic keratophakia for the correction of aphakia has several inherent advantages over alternative forms of refractive surgery which use lathed corneal tissue. For example, the ability to produce a synthetic lens to precise specifications before surgery is a dramatic advantage over the use of lathed tissue lenses whose refractive properties cannot be determined until weeks or months after the lens is in place on the recipient cornea. Synthetic materials appear to behave in a predictable manner and are biocompatible. Both polysulfones and hydrogel materials can be used to correct aphakia in clinical situations where other modalities are less appropriate.

Animals↗
PubMed1988

Extended-wear contact lenses for the treatment of pediatric aphakia.

The practicality of extended-wear contact lenses in the refractive correction of pediatric aphakia was assessed with 240 eyes in 184 patients. Patient ages at the time of contact lens fitting ranged from 18 days to 9.8 years. One hundred forty-one eyes were fit from 1 day to 55 months postoperatively and then followed for 6 months to 5.7 years (average, 29 months). Only five patients lost more than five lenses. The overall loss rate was less than one lens per year of follow-up. No patient had contact lens-related complications with permanent visual sequelae. Only 14% of patients had contact lens problems or factors related to parental inability to care for the lens which resulted in discontinuation of contact lens therapy. The authors were unable to identify any subset of patients who should be considered for primary surgical optical correction of their aphakia.

Aphakia, Postcataract↗
PubMed1988

The correction of aphakia in infants with hydrogel extended-wear contact lenses. Corneal studies.

Although hydrogel extended-wear contact lenses (EWCLs) have been used extensively in the correction of aphakia in neonates, little is known about the effects of these lenses on infant corneas. Recent studies have demonstrated that long-term contact lenses can induce endothelial morphometric changes, including an increased coefficient of variation (CV) of mean endothelial cell area. Using wide-field specular microscopy, the authors studied 11 eyes of 10 patients, 1 to 3 years of age who, after lensectomy for congenital cataracts, wore EWCLs for the correction of aphakia. Except for two corneas in which increased pachometric readings and CV developed after repeated episodes of lens loss and inflammation, the EWCL were well tolerated and associated with few complications in this study.

Aphakia, Postcataract↗
PubMed1988

Binocular function in unilateral aphakia. Correlation with aniseikonia and stereoacuity.

Aniseikonia and stereoacuity were measured in patients with unilateral aphakia, most of whom were postoperative senile cataract cases. The New Aniseikonia test was used to evaluate aniseikonia and the Titmus Stereotest to measure stereoacuity. Ninety cases were studied, 57 (63.3%) of which had intraocular lens (IOL) implants; 27 (30%) had extended-wear soft contact lenses; and six (6.7%) had spectacle lenses. In the IOL group, aniseikonia averaged 2.8%, and 39 patients (68.4%) had good stereoacuity. In the contact lens group, aniseikonia averaged 4.6%, and 11 (40.7%) had good stereoacuity. In the spectacle lens group, aniseikonia averaged 17.8%; none of the patients had good stereoacuity. The authors concluded that in cases with unilateral aphakia, correction with an IOL implant is superior to the other alternatives in achieving good binocular function.

Adolescent↗
PubMed1988

The nationwide study of epikeratophakia for aphakia in older children.

A nationwide study of epikeratophakia for aphakia in older children was conducted from March 1984 to March 1986. Sixty-three patients, 8 to 18 years of age, underwent this procedure in 65 eyes. Twenty-eight patients had congenital cataracts and 35 had traumatic cataracts. Fifty-one of the 65 eyes were aphakic at the time of surgery (secondary procedures). All surgeries were successful; no tissue lenses were lost or removed. Postoperatively, 73% of the patients were within 3 diopters (D) of emmetropia. The patients with congenital cataracts gained an average of one Snellen line of best-corrected visual acuity; patients with traumatic cataracts lost an average of one Snellen line of best-corrected visual acuity. In older pediatric patients, epikeratophakia appears to be a safe and effective procedure for the correction of aphakia.

Aphakia↗
PubMed2003

Management of traumatic aniridia and aphakia with an iris reconstruction implant.

We describe the clinical features and management of a 36-year-old man with aniridia and aphakia following blunt ocular trauma. Examination showed partial aniridia and aphakia. We discuss the various options available in the management of this patient and describe the surgical technique involved in the implantation of an iris reconstruction implant.

Adult↗
PubMed2003

Trabeculectomy with or without mitomycin-C for paediatric glaucoma in aphakia and pseudophakia following congenital cataract surgery.

PURPOSE: To evaluate the safety and efficacy of trabeculectomy with or without mitomycin-C (MMC) in the management of glaucoma in aphakia and pseudophakia following congenital cataract surgery. PATIENTS AND METHODS: All patients of glaucoma with aphakia or pseudophakia who underwent trabeculectomy with or without MMC from January 1989 to April 2000 were included. The medical records of 19 consecutive patients (23 eyes) were reviewed. Data collected from a retrospective chart review were analysed. Outcome measures were evaluated using Kaplan-Meier survival analysis. Pre- and postoperative intraocular pressures (IOPs), visual acuities, success rate, bleb characteristics, surgical failure and complications were the main outcome measures. Successful IOP control was defined as an IOP between 6 and 21 mmHg, without antiglaucoma medications, without further antiglaucoma surgery and without any sight-threatening complication. RESULTS: The mean age of patients was 8.8+/-5.5 years at the time of trabeculectomy with MMC compared to 11.0+/-12.4 years for trabeculectomy without MMC. Eight patients underwent trabeculectomy with MMC and 11 patients underwent trabeculectomy without MMC. There was no statistically significant difference between the two groups in terms of visual acuity, IOP, antiglaucoma medications, age at cataract surgery and at trabeculectomy. The IOP reduced from a preoperative level of 34.2+/-8.9 mmHg (range: 20-52) to a postoperative level of 18.4+/-12.2 mmHg (range: 2-60) with a mean follow-up of 24.2+/-17.9 months. The mean reduction in IOP in the MMC group was 15.5+/-17.3 and 16.3+/-13.8 mmHg in the other group (P = 0.967). Overall, complete success was achieved in 36.8%, qualified success in 21.1% and surgical failure in 42.1% of patients with a mean follow-up of 24.2+/-17.9 months. There was no difference in the success between the two groups at the last follow-up. One patient developed bleb-related endophthalmitis in both eyes following trabeculectomy with MMC. CONCLUSIONS: The success rate of trabeculectomy in glaucoma following congenital cataract surgery was 36.8% at the end of 3 years. The present study proves a poor success rate of trabeculectomy in a small series of aphakic Asian Indian patients even with the use of MMC.

Adolescent↗
PubMed1985

[Recommendations for the evaluation of complicated aphakia in private accident insurance].

An evaluation of cases in which an expert opinion was obtained during the last 2 years shows that only one-third of patients with traumatic aphakia and a 20/30 loss of vision are adequately assessed. If there are further consequences of the accident (complicated aphakia) they should also be taken into account when assessing loss of vision. A simple method of doing this is described on the basis of three examples.

Adolescent↗
PubMed1982

[Contact lens correction of post-traumatic unilateral aphakia. Late visual and orthoptic results].

From 1978 to 1981 total of 122 perforating eye injuries were treated in the eye department of the Salzburg provincial clinic. In 25% of the cases treated the opacified lens had to be removed. The authors followed up 35 patients with unilateral post-traumatic aphakia. Of these, 27 proved suitable candidates for contact lenses. Visual function was good in 15 patients, but reduced in 12 due to post-traumatic changes. Ten patients achieved binocular vision, while in 12 it was possible to restore binocular vision by appropriate measures. The paper deals particular with the restoration of binocular vision and maintenance of binocular function in cases of unilateral post-traumatic aphakia.

Adolescent↗
PubMed2006

Homozygous nonsense mutation in the FOXE3 gene as a cause of congenital primary aphakia in humans.

Congenital primary aphakia (CPA) is a rare developmental disorder characterized by the absence of lens, the development of which is normally induced during the 4th-5th wk of human embryogenesis. This original failure leads, in turn, to complete aplasia of the anterior segment of the eye, which is the diagnostic histological criterion for CPA. So far, the genetic basis for this human condition has remained unclear. Here, we present the analysis of a consanguineous family with three siblings who had bilateral aphakia, microphthalmia, and complete agenesis of the ocular anterior segment. We show that a null mutation in the FOXE3 gene segregates and, in the homozygous state, produces the mutant phenotype in this family. Therefore, this study identifies--to our knowledge, for the first time--a causative gene for CPA in humans. Furthermore, it indicates a possible critical role for FOXE3 very early in the lens developmental program, perhaps earlier than any role recognized elsewhere for this gene.

Adult↗
PubMed1997

Drug distribution in the vitreous humor of the human eye: the effects of aphakia and changes in retinal permeability and vitreous diffusivity.

The majority of eyes that receive drug therapy exhibit some form of pathophysiological degradation. Two common pathophysiological states are retinal inflammation, which results in breakdown of the blood-retinal barrier, and aphakia. The purpose of this study was to examine the effects of aphakia and changes in retinal permeability and vitreous diffusivity on drug distribution in the vitreous humor of the human eye. The study was performed using a finite element model that accurately accounts for the vitreous geometry and boundary conditions. Intravitreal injection is the most common method for treating posterior segment disorders; therefore, this administration method was simulated using the models. Elimination from aphakic and phakic eyes was compared for four extreme injection locations and for two retinal permeabilities. When the retinal permeability was fixed at 5.0 x 10(-5) cm/s, increasing the drug diffusivity through the vitreous from 5.4 to 10(-7) to 2.4 x 10(-5) cm2/s decreased the half-life of drug from 64 hours to 2.7 hours. When the drug diffusivity was fixed at 5.6 x 10(-6) cm2/s, increasing the retinal permeability of the drug from 1.0 x 10(-7) to 1.0 x 10(-4) cm/s decreased the half-life of drug from 44 to 7 hours. Therefore, drug diffusivity and retinal permeability are key factors that influence elimination from the vitreous, and must be considered, particularly if the blood retinal barrier has been compromised. Faster drug elimination was observed in aphakic eyes than in phakic eyes, especially for drugs with a low retinal permeability and injected close to the lens capsule. Injection position is also important if the drug is injected in close proximity to a primary elimination barrier.

Aphakia↗
PubMed2000

Deletion in the promoter region and altered expression of Pitx3 homeobox gene in aphakia mice.

Mouse aphakia (ak) is a recessive phenotype that spontaneously occurs in the 129/Sv-SlJ strain and is characterized by small eyes that lack a lens. We have recently identified a homeobox-containing gene, Pitx3, and have shown that it is expressed in the developing lens and maps to chromosome 19 close to ak in mouse. Human PITX3 gene was found to underlie anterior segment dysgenesis and cataracts. We have now obtained the entire sequence of the mouse Pitx3 gene including 10 kb of the 5' region and 5 kb of the 3' region. Of several microsatellite repeat regions identified within the Pitx3 sequence, one was informative for linkage analysis. No recombination was observed between ak and the Pitx3 marker, indicating that these two loci are closely linked (0.2 +/- 0.2 cM). Additionally, Pitx3 transcripts were not detected in the ak/ak mice either in the lens placode or at later developmental stages of the lens by in situ hybridization. Since no differences were previously found between ak/ak and wild-type sequences in the Pitx3 coding region, we hypothesized that an etiologic mutation is located in the promoter or other regulatory regions. To test this hypothesis we studied the 5' flanking region of the Pitx3 gene. This analysis revealed a deletion of 652 bp located 2.5 kb upstream from the start point of the Pitx3 5' UTR sequence in ak/ak mice. The deletion co-segregated with the ak mutation and was not detected in 16 samples from 10 different mouse strains including the founder strains. Analysis of the 652 bp region identified sequences similar to consensus binding sites for transcription factors AP-2 and Maf that were shown to play a critical role in lens determination. These lines of evidence suggest that the abnormal ocular development in the aphakia mouse is due to the deletion upstream of the Pitx3 gene.

Acetyltransferases↗
PubMed1981

Extended wear contact lenses for aphakia.

The current modality for correcting unilateral aphakia is by the use of daily wear hard and soft contact lenses and by the use of intraocular lens implants. The use of the Cooper Permalens soft contact lens as an extended wear lens for correction of aphakia was investigated in 177 eyes. The relative merits of the extended wear lens are discussed with emphasis on fit, visual function, and contact lens-related problems.

Aphakia, Postcataract↗
PubMed1981

Reverse Galilean telescopic spectacles in unilateral aphakia.

Minimizing aniseikonia in unilateral aphakia is often a difficult task. A case is presented in which a patient preferred a reverse Galilean telescopic spectacle of his own design to a contact lens. The design of the spectacles and the patient's visual performance with them are described. A reverse Galilean telescopic spectacle should not be excluded from the therapeutic alternatives in unilateral aphakia.

Aphakia, Postcataract↗