Pathogenic variants in the CYP21A2 gene cause isolated autosomal dominant congenital posterior polar cataracts

BACKGROUND

Congenital cataracts are the most common cause of visual impairment worldwide. Inherited cataract is a clinically and genetically heterogeneous disease. Here we report disease-causing variants in a novel gene, CYP21A2, causing autosomal dominant posterior polar cataract. Variants in this gene are known to cause autosomal recessive congenital adrenal hyperplasia (CAH).

METHODS

Using whole-exome sequencing (WES), we have identified disease-causing sequence variants in two families of British and Irish origin, and in two isolated cases of Asian-Indian and British origin. Bioinformatics analysis confirmed these variants as rare with damaging pathogenicity scores. Segregation was tested within the families using direct Sanger sequencing.

RESULTS

A nonsense variant NM_000500.9 c.955 C > T; p.Q319* was identified in CYP21A2 in two families with posterior polar cataract and in an isolated case with unspecified congenital cataract phenotype. This is the same variant previously linked to CAH and identified as Q318* in the literature. We have also identified a rare missense variant NM_000500.9 c.770 T > C; p.M257T in an isolated case with unspecified congenital cataract phenotype.

CONCLUSION

This is the first report of separate sequence variants in CYP21A2 associated with congenital cataract. Our findings extend the genetic basis for congenital cataract and add to the phenotypic spectrum of CYP21A2 variants and particularly the CAH associated Q318* variant. CYP21A2 has a significant role in mineralo- and gluco-corticoid biosynthesis. These findings suggest that CYP21A2 may be important for extra-adrenal biosynthesis of aldosterone and cortisol in the eye lens.

Variants in PAX6, PITX3 and HSF4 causing autosomal dominant congenital cataracts

Background

Lens development is orchestrated by transcription factors. Disease-causing variants in transcription factors and their developmental target genes are associated with congenital cataracts and other eye anomalies.

Methods

Using whole exome sequencing, we identified disease-causing variants in two large British families and one isolated case with autosomal dominant congenital cataract. Bioinformatics analysis confirmed these disease-causing mutations as rare or novel variants, with a moderate to damaging pathogenicity score, with testing for segregation within the families using direct Sanger sequencing.

Results

Family A had a missense variant (c.184 G>A; p.V62M) in PAX6 and affected individuals presented with nuclear cataract. Family B had a frameshift variant (c.470–477dup; p.A160R*) in PITX3 that was also associated with nuclear cataract. A recurrent missense variant in HSF4 (c.341 T>C; p.L114P) was associated with congenital cataract in a single isolated case.

Conclusions

We have therefore identified novel variants in PAX6 and PITX3 that cause autosomal dominant congenital cataract.

The genetic landscape of crystallins in congenital cataract

Background

The crystalline lens is mainly composed of a large family of soluble proteins called the crystallins, which are responsible for its development, growth, transparency and refractive index. Disease-causing sequence variants in the crystallins are responsible for nearly 50% of all non-syndromic inherited congenital cataracts, as well as causing cataract associated with other diseases, including myopathies. To date, more than 300 crystallin sequence variants causing cataract have been identified.

Methods

Here we aimed to identify the genetic basis of disease in five multi-generation British families and five sporadic cases with autosomal dominant congenital cataract using whole exome sequencing, with identified variants validated using Sanger sequencing. Following bioinformatics analysis, rare or novel variants with a moderate to damaging pathogenicity score, were filtered out and tested for segregation within the families.

Results

We have identified 10 different heterozygous crystallin variants. Five recurrent variants were found: family-A, with a missense variant (c.145C>T; p.R49C) in CRYAA associated with nuclear cataract; family-B, with a deletion in CRYBA1 (c.272delGAG; p.G91del) associated with nuclear cataract; and family-C, with a truncating variant in CRYGD (c.470G>A; W157*) causing a lamellar phenotype; individuals I and J had variants in CRYGC (c.13A>C; T5P) and in CRYGD (c.418C>T; R140*) causing unspecified congenital cataract and nuclear cataract, respectively. Five novel disease-causing variants were also identified: family D harboured a variant in CRYGC (c.179delG; R60Qfs*) responsible for a nuclear phenotype; family E, harboured a variant in CRYBB1 (c.656G>A; W219*) associated with lamellar cataract; individual F had a variant in CRYGD (c.392G>A; W131*) associated with nuclear cataract; and individuals G and H had variants in CRYAA (c.454delGCC; A152del) and in CRYBB1 (c.618C>A; Y206*) respectively, associated with unspecified congenital cataract. All novel variants were predicted to be pathogenic and to be moderately or highly damaging.

Conclusions

We report five novel variants and five known variants. Some are rare variants that have been reported previously in small ethnic groups but here we extend this to the wider population and record a broader phenotypic spectrum for these variants.

Whole Exome Sequencing Reveals Novel and Recurrent Disease-Causing Variants in Lens Specific Gap Junctional Protein Encoding Genes Causing Congenital Cataract

Pediatric cataract is clinically and genetically heterogeneous and is the most common cause of childhood blindness worldwide. In this study, we aimed to identify disease-causing variants in three large British families and one isolated case with autosomal dominant congenital cataract, using whole exome sequencing. We identified four different heterozygous variants, three in the large families and one in the isolated case. Family A, with a novel missense variant (c.178G>C, p.Gly60Arg) in GJA8 with lamellar cataract; family B, with a recurrent variant in GJA8 (c.262C>T, p.Pro88Ser) associated with nuclear cataract; and family C, with a novel variant in GJA3 (c.771dupC, p.Ser258GlnfsTer68) causing a lamellar phenotype. Individual D had a novel variant in GJA3 (c.82G>T, p.Val28Leu) associated with congenital cataract. Each sequence variant was found to co-segregate with disease. Here, we report three novel and one recurrent disease-causing sequence variant in the gap junctional protein encoding genes causing autosomal dominant congenital cataract. Our study further extends the mutation spectrum of these genes and further facilitates clinical diagnosis. A recurrent p.P88S variant in GJA8 causing isolated nuclear cataract provides evidence of further phenotypic heterogeneity associated with this variant.

Visual fields in patients with multifocal intraocular lens implants and monovision: an exploratory study

PURPOSE

To assess the difference in binocular visual fields (VFs) in patients who underwent bilateral cataract surgery with either multifocal (MF; Tecnis ZM900, AMO) intraocular lenses (IOLs) or monofocal IOLs with powers adjusted to give monovision (MV; Akreos AO, Bausch&Lomb).

SETTING

St George's & Moorfields Eye Hospital, London.

METHODS

Prospective exploratory study. Binocular Esterman VFs (Humphrey Field Analyser II) were compared between 10 participants with MV and 16 participants with MF IOLs. The dominant eye in MV participants had 0 to -0.50DS and the non-dominant eye had between -1.0DS and -1.5DS. Best-corrected Snellen visual acuity for all 52 eyes was six out of nine or better. The main outcome measure was Esterman Efficiency Score. Incidence of suboptimal VF results (≥1 Unseen Locations--ULs) and mean testing times in the two groups were compared.

RESULTS

There was no statistically significant difference in the incidence of suboptimal VF results in these two groups (P=0.662). Test durations in the two groups were not significantly different (P=0.650). However, 3/10 MV plots (33%) had markedly suboptimal right hemi-fields (distance-dominant eye) compared with 0/15 MF plots. Additionally, the MV group accounted for 79% of total ULs (20/29) and all these ULs were distributed in areas outside or bordering the true binocular VFs.

CONCLUSIONS

All included VFs met the UK driving standards criteria. The pattern of VF defects encountered in the MV group is of interest because the majority of ULs (13/20; 65%) corresponded to the monocular VFs of the distance-dominant eye.

National survey of the management of eye emergencies in the accident and emergency departments by senior house officers: 10 years on--has anything changed?

OBJECTIVE

To assess changes in basic ophthalmic training of accident and emergency (A&E) senior house officers (SHOs) in the last 10 years, their own perceived level of confidence and the availability of appropriate equipment in their departments.

METHODS

A standardised structured questionnaire from a telephone survey carried out in 1993 was used. One SHO from each A&E department listed in the British Association of Emergency Medicine directory of 2003 was chosen at random and interviewed.

RESULTS

168 A&E departments were contacted and 133 SHOs were successfully interviewed (response rate 79.2%). The number of A&E departments with a slit lamp increased by 25.7% from 1993, and slit lamp training increased by 21%. There was no significant change in the prevalence of training in the management of eye emergencies (74.0% in 1993 vs 77.4% in 2003) and the proportion of SHOs who felt confident in dealing with these cases was unchanged.

CONCLUSIONS

A&E departments are better equipped with slit lamps 10 years on, and staff are being trained to use them. This has unfortunately not improved the confidence levels in dealing with eye emergencies, reflecting the lack of adequate basic ophthalmic training for A&E SHOs. Recent changes in postgraduate medical training could provide a platform to bring about the changes required.

Early structured core training of junior trainees in ophthalmology

The implementation of modernizing medical careers (MMC) has resulted in some specialties being allocated very inexperienced trainees such as ophthalmology. We aim to describe the process of implementation of MMC and how it may affect the service provision in smaller specialities such as ophthalmology. A methodical approach in a district hospital setting was used to provide early core training to such trainees involving managerial support. The quality of service provided by newer trainees can be enhanced by providing early structured training during induction to create an atmosphere of enthusiasm and continued learning. This example can be used in other units and specialties.

Screening for ocular surface disease in the intensive care unit

PURPOSE

Ventilated patients in the intensive care unit (ICU) often develop exposure keratopathy. This predisposes to the development of bacterial keratitis, which in ICU is often bilateral, with a high risk of perforation. As regular examinations of all ventilated patients by ophthalmologists would be impractical, the purpose of this study was to assess whether ICU staff can screen reliably for keratopathy.

METHODS

A prospective study was performed in a general adult ICU. Twice each week, two junior ICU doctors examined the lid position and ocular surface of all patients who had been continuously sedated for more than 24 h, using fluorescein and a pen torch with a blue filter. An ophthalmologist performed similar examinations using a portable slit lamp.

RESULTS

A total of 48 ocular examinations were performed in 18 patients. Exposure keratopathy was found by the ophthalmologist in 37.5% of examinations and by ICU doctors in 31.3% of examinations. ICU doctors had a sensitivity of 77.8% and a specificity of 96.7% in detecting keratopathy, when compared with the findings of the ophthalmologist. All cases missed by ICU doctors had punctate erosions of less than 5% of the corneal surface. Keratopathy was significantly commoner in patients with incomplete lid closure than in patients with closed lids (70.0 vs 28.9%; two-tailed Fisher's exact test P=0.027).

CONCLUSIONS

ICU staff can perform screening examinations for exposure keratopathy with reasonable sensitivity and specificity. Regular screening by ICU staff would facilitate appropriate treatment of exposure keratopathy and promote earlier identification of cases of keratitis.

Opacification of Array SA40N silicone multifocal intraocular lens

We report opacification of 2 multifocal intraocular lenses (IOLs). Patients with these IOLs may be more likely to require IOL explantation than those with monofocal IOLs.

Intraoperative complications of cataract surgery in the very old

AIM

To identify whether the risk of an intraoperative complication of phakoemulsification cataract surgery increases with age.

METHODS

1441 consecutive patients undergoing phakoemulsification cataract surgery were assessed preoperatively, and data on the occurrence of intraoperative complications were collected prospectively. Data were entered into a computerised database, and logistic regression was used to examine evidence of an association between age and the risk of an intraoperative complication. In addition, the rates of intraoperative complications were compared between patients > or =88 years and those <88 years, and between patients > or =96 years and those <96 years.

RESULTS

No significant association was found between age and the risk of an intraoperative complication. The authors found little evidence that patients > or =88 years were at a greater risk of an intraoperative complication than those <88 years, or that those > or =96 years are at increased risk; however, numbers were small.

CONCLUSIONS

These results suggest that age alone is not a major risk factor for any intraoperative complications occurring during phakoemulsification cataract surgery. This has implications not just for tailoring the risk of complications occurring to individual patients but also for meaningful comparisons between national complication rates and those of individual surgeons, and better selection of cases suitable for instruction.

A system for preoperative stratification of cataract patients according to risk of intraoperative complications: a prospective analysis of 1441 cases

AIM

To devise a simple, robust scoring system for assessing the risk of intraoperative complications in patients undergoing cataract surgery.

METHODS

1441 consecutive patients undergoing phacoemulsification cataract surgery were assessed preoperatively according to weighted criteria. According to the points of risk they accumulated using this system, the patients were preoperatively allocated to one of four risk groups. Data were prospectively collected on the occurrence of intraoperative complications and entered into a computerised database. The total rate of intraoperative complications for each risk group as well as the rate of each reported complication for each risk group were calculated.

RESULTS

The rate of intraoperative complications increased in frequency through the risk groups: 1 = 4.32%, 2 = 7.45%, 3 = 13.48%, and 4 = 32.00% (p<0.001). Furthermore, the following complications also increased in frequency through the risk groups in their own right (p<0.05 in each case): posterior capsule rupture, vitreous loss, incomplete capsulorrhexis, zonule dehiscence, wound burn/leak, and lost nuclear fragment into vitreous cavity.

CONCLUSION

These results suggest that candidates for cataract surgery can be simply and uniformly assessed preoperatively and categorised to a "risk group" according to their risk of intraoperative complications. This allows for: (1) individualised counselling on the chances of operative complications, (2) meaningful comparisons between national complication rates and those of individual units or surgeons, and (3) better selection of cases suitable for instruction.

Consequence of perforation during peribulbar anesthesia in an only eye

A patient with a blind fellow eye had cataract surgery in the right eye; anesthesia comprised an intraocular injection of lidocaine and bupivacaine. Forty-eight hours after surgery, visual acuity in the right eye was light perception (LP). Three days later, fundus examination showed inferotemporal hemorrhage, retinal whitening consistent with needle tracking, and a diffusely pale optic disc in the operated eye. Computed tomography showed an intact optic nerve in both eyes and high-density vitreal lesions in the right eye. Laser photocoagulation was applied to the retinal break. We believe that a jet stream of anesthetic agent may have transiently increased intraocular volume enough to occlude the central retinal artery. Although the retina remained attached, visual acuity failed to improve beyond LP.

Effect of visual acuity on biometry prediction error after cataract surgery

PURPOSE

To determine the effect of visual acuity on biometry prediction error.

SETTING

Postgraduate teaching hospital.

METHODS

The study was an observational case series of the first operated eye of 2149 consecutive patients who had cataract surgery. Biometry prediction error was defined as the difference between the planned refraction determined by biometry and the spherical equivalent of the final refraction. The principal outcome measure was the percentage of eyes within +/-1.00 diopter (D) of the intended refraction. This outcome was calculated for patients with visual loss caused by cataract alone, defined as eyes with a postoperative acuity of 6/6 or better, and eyes with different levels of postoperative visual acuity.

RESULTS

Complete data were available for 1978 eyes (92%). Of these, 1438 (73%) were within +/-1.00 D of the intended refraction. When the final corrected visual acuity was 6/6 or better, the percentage of eyes within +/-1.00 D of the predicted refraction was at least 78%. When the preoperative acuity was worse than 6/60, 74% in the counting fingers group and 69% in the hand movements group with a final corrected acuity of 6/6 or better were within +/-1.00 D. This trend bordered on statistical significance (P =.05). There was a rapid reduction in the percentage of eyes within +/-1.00 D of the intended refraction as the postoperative acuity decreased because of ocular comorbidity, with a statistically significant difference between eyes with a postoperative acuity of 6/6 or better and each group with an acuity of 6/9 or worse (P<.01).

CONCLUSIONS

In eyes without visually significant ocular comorbidity, cataract must reduce vision to 6/60 or worse before there is an increase in biometry prediction error. In contrast, ocular comorbidity that reduces the postoperative acuity causes an early and marked increase in biometry prediction error.

Visual outcome in patients with isolated autosomal dominant congenital cataract

OBJECTIVE

To determine the visual outcome and surgical complication rates of patients with isolated inherited congenital cataract.

DESIGN

Retrospective noncomparative case series.

PARTICIPANTS

Patients and their families were ascertained from the genetic eye clinic and outpatient databases of Moorfields Eye Hospital, London, and invited to participate in the study. Four hundred twenty-two individuals from 72 pedigrees with this form of autosomal dominant cataract underwent ophthalmologic assessment.

MAIN OUTCOME MEASURES

Visual acuity and surgical complications (glaucoma, retinal detachment, amblyopia).

RESULTS

In this study 49.4% of patients (46.8% of those operated) achieved a visual acuity (VA) of 20/40 or better, 35.9% (36.1% of those operated) a VA between 20/50 and 20/200, and 14.7% (17.1% of those operated) worse than 20/200. Opacities that were more diffuse or did not lie close to the visual axis were associated with a better prognosis for vision; 6.6% had glaucoma and 5.0% had retinal detachment develop.

CONCLUSIONS

Patients with isolated inherited congenital cataract have a better visual and surgical outcome than those with coexisting ocular and systemic abnormalities. The improved prognosis is related in part to the lack of other developmental abnormalities of the eye, and, because inherited cataracts are often partial at birth, surgery may be delayed to later infancy and childhood when there is a lower incidence of surgical complications and refractive correction is easier. Certain inherited phenotypes (lamellar, pulverulent, polymorphic, coralliform, and cortical) also seem to have a better prognosis, and this should be borne in mind when counseling these families. A large number of the patients in this study underwent surgery many years previously, when surgical outcomes were less favorable, and thus the results of this study establish only a minimum acuity dataset for the purposes of counseling.

Visual outcome following posterior capsule rupture during cataract surgery

AIM

To determine the relative risk of a poor visual outcome following posterior capsule rupture during cataract surgery.

METHODS

Prospective data were collected on consecutive eyes undergoing cataract extraction. The patient's age, preoperative visual acuity, ocular comorbidity, grade of surgeon, and operative complications were documented. The best spectacle corrected visual acuity was recorded at discharge from the hospital service.

RESULTS

From a total of 1533 cases, 1420 (92.6%) eyes had complete follow up data. Posterior capsule rupture occurred in 59 (4.1%) cases. Eyes with posterior capsule rupture were 3.8 times more likely to have a final best spectacle corrected visual acuity less than 6/12.

CONCLUSIONS

Eyes having posterior capsule rupture during cataract surgery have a significant risk of reduced visual acuity.

Clinical and genetic heterogeneity in autosomal dominant cataract

AIMS

To determine the different morphologies of autosomal dominant cataract (ADC), assess the intra- and interfamilial variation in cataract morphology, and undertake a genetic linkage study to identify loci for genes causing ADC and detect the underlying mutation.

METHODS

Patients were recruited from the ocular genetic database at Moorfields Eye Hospital. All individuals underwent an eye examination with particular attention to the lens including anterior segment photography where possible. Blood samples were taken for DNA extraction and genetic linkage analysis was carried out using polymorphic microsatellite markers.

RESULTS

292 individuals from 16 large pedigrees with ADC were examined, of whom 161 were found to be affected. The cataract phenotypes could all be described as one of the eight following morphologies-anterior polar, posterior polar, nuclear, lamellar, coralliform, blue dot (cerulean), cortical, and pulverulent. The phenotypes varied in severity but the morphology was consistent within each pedigree, except in those affected by the pulverulent cataract, which showed considerable intrafamilial variation. Positive linkage was obtained in five families; in two families linkage was demonstrated to new loci and in three families linkage was demonstrated to previously described loci. In one of the families the underlying mutation was isolated. Exclusion data were obtained on five families.

CONCLUSIONS

Although there is considerable clinical heterogeneity in ADC, the phenotype is usually consistent within families. There is extensive genetic heterogeneity and specific cataract phenotypes appear to be associated with mutations at more than one chromosome locus. In cases where the genetic mutation has been identified the molecular biology and clinical phenotype are closely associated.

Connexin 50 mutation in a family with congenital "zonular nuclear" pulverulent cataract of Pakistani origin

Inherited cataract is a clinically and genetically heterogeneous disease that most often presents as a congenital autosomal dominant trait. Here we report linkage of a three-generation family of Pakistani origin with autosomal dominant cataract "zonular nuclear" pulverulent type (CZNP) on chromosome 1q21.1. Genome wide-linkage analysis excluded all the known cataract loci except on chromosome 1q. Significantly positive 2-point lod score values (Z=3.01 at theta=0) were obtained for markers D1S305 and D1S2721, which are known to flank the gene for connexin 50 (Cx50) or gap junction protein alpha-8 (Gja8). Previously a mutation in this gene has been reported in a British family with zonular pulverulent cataract (CZP). Here we describe a second mutation (E48K) in connexin 50 that confirms the involvement of this gene in cataractogenesis.

Connexin46 mutations in autosomal dominant congenital cataract

Loci for autosomal dominant "zonular pulverulent" cataract have been mapped to chromosomes 1q (CZP1) and 13q (CZP3). Here we report genetic refinement of the CZP3 locus and identify underlying mutations in the gene for gap-junction protein alpha-3 (GJA3), or connexin46 (Cx46). Linkage analysis gave a significantly positive two-point LOD score (Z) at marker D13S175 (maximum Z [Zmax]=>7.0; maximum recombination frequency [thetamax] =0). Haplotyping indicated that CZP3 probably lies in the genetic interval D13S1236-D13S175-D13S1316-cen-13pter, close to GJA3. Sequencing of a genomic clone isolated from the CZP3 candidate region identified an open reading frame coding for a protein of 435 amino acids (47,435 D) that shared approximately 88% homology with rat Cx46. Mutation analysis of GJA3 in two families with CZP3 detected distinct sequence changes that were not present in a panel of 105 normal, unrelated individuals. In family B, an A-->G transition resulted in an asparagine-to-serine substitution at codon 63 (N63S) and introduced a novel MwoI restriction site. In family E, insertion of a C at nucleotide 1137 (1137insC) introduced a novel BstXI site, causing a frameshift at codon 380. Restriction analysis confirmed that the novel MwoI and BstXI sites cosegregated with the disease in families B and E, respectively. This study identifies GJA3 as the sixth member of the connexin gene family to be implicated in human disease, and it highlights the physiological importance of gap-junction communication in the development of a transparent eye lens.

Anterior polar cataract: clinical spectrum and genetic linkage in a single family

Anterior polar cataract can occur as a sporadic finding, in association with other ocular abnormalities or as an inherited, autosomal dominant disorder. We have demonstrated linkage in a family with autosomal dominant anterior polar cataract to the short arm of chromosome 17, locating the gene to the region 17p12-13. All affected members of this large family had an opacity at the anterior pole of the lens that varied only in size and the effect on visual acuity. Anterior polar cataract is thought to have a minimal effect on visual acuity although in the affected members of this family there was a high incidence of unilateral amblyopia.

A missense mutation in the human connexin50 gene (GJA8) underlies autosomal dominant "zonular pulverulent" cataract, on chromosome 1q

CZP1, a locus for autosomal dominant "zonular pulverulent" cataract, previously had been linked with the Duffy blood-group-antigen locus on chromosome 1q. Here we report genetic refinement of the CZP1 locus and show that the underlying mutation is present in GJA8, the gene for connexin50. To map the CZP1 locus we performed linkage analysis using microsatellite markers on two distantly related branches of the original Ev. pedigree, which now spans eight generations. Significantly positive two-point LOD score (Z) values were obtained for markers D1S2669 (maximum Z [Zmax] = 4.52; maximum recombination frequency [thetamax] = 0) and D1S514 (Zmax = 4.48; thetamax = 0). Multipoint analysis gave Zmax = 5.22 (thetamax = 0) at marker D1S2669. Haplotyping indicated that CZP1 probably lies in the genetic interval D1S2746-(20.6 cM)-D1S2771. Sequence analysis of the entire protein-coding region of the GJA8 gene from the pedigree detected a C-->T transition in codon 88, which introduced a novel MnlI restriction-enzyme site that also cosegregated with the cataract. This missense mutation is predicted to result in the nonconservative substitution of serine for a phylogenetically conserved proline (P88S). These studies provide the first direct evidence that GJA8 plays a vital role in the maintenance of human lens transparency and identify the genetic defect believed to underlie the first inherited disease to be linked to a human autosome.

A new locus for dominant "zonular pulverulent" cataract, on chromosome 13

Inherited cataract is a clinically and genetically heterogeneous disease that most often presents as a congenital autosomal dominant trait. Here we report the linkage of a new locus for dominant "zonular pulverulent" cataract (CZP) to chromosome 13. To map the CZP locus we performed molecular-genetic linkage analysis using microsatellite markers in a five-generation English pedigree. After exclusion of eight known loci and several candidate genes for autosomal dominant cataract, we obtained significantly positive LOD scores (Z) for markers D13S175 (maximum Z [Zmax] = 4.06; maximum recombination frequency [theta max] = 0) and D13S1236 (Zmax = 5.75, theta max = 0). Multipoint analysis gave Zmax = 6.62 (theta max = 0) at marker D13S175. Haplotype data indicated that CZP probably lies in the centromeric region of chromosome 13, provocatively close to the gene for lens connexin46.

Resource management of cataract patients: can visual rehabilitation be achieved in three visits?

PURPOSE

To assess the feasibility and acceptability of reduced postoperative follow-up after phacoemulsification using a scleral tunnel technique.

SETTING

Cataract service of a large free-standing eye hospital in a capital city.

METHODS

In this pilot study, patients with age-related cataract requiring surgery were prospectively recruited to a standardized management protocol, the three-episode model, with assessment by an independent observer. Main outcome measures were number of postoperative visits, patient satisfaction, and refractive error at 2 and 6 weeks postoperatively.

RESULTS

Almost 90% of patients could be managed within this model of care. Patient satisfaction was high; no patient requested further hospital visits. Mean change in refractive error between 2 and 6 weeks was 0.34 diopters (D), with a modal value of 0 D. Patients were able to obtain spectacles 2 weeks postoperatively because little change in refraction occurs over the next month.

CONCLUSION

The three-episode model for the management of patients with cataract could result in significant financial savings. Such savings could be used to treat patients with cataract who otherwise would not have treatment or would have their surgery delayed.

Posterior capsule opacification following diabetic extracapsular cataract extraction

Review was performed of extracapsular cataract extraction with posterior chamber lens implantation in 90 diabetic patients and 263 non-diabetic patients. There was a higher incidence of posterior capsular opacification as judged by the requirement for Nd:YAG posterior capsulotomy in patients with non-proliferative (12/35, 34%) or quiescent proliferative diabetic retinopathy (8/18, 44%) than in non-diabetic patients (48/263, 18%) (Mantel-Haenszel p = 0.04). Although subgroup analysis showed a higher incidence of posterior capsule opacification in diabetics with non-proliferative or quiescent proliferative retinopathy than in diabetics without retinopathy, this was not statistically significant (Mantel-Haenszel p = 0.19 and p = 0.07, respectively). Following cataract surgery in diabetics with retinopathy, frequent review and prompt management of posterior capsular opacification is recommended, to maintain adequate fundus visualisation at a time when deterioration of retinopathy is likely.