Clinical features of codon 172 RDS macular dystrophy: similar phenotype in 12 families

OBJECTIVE

To report the phenotype associated with the codon 172 RDS (gene for retinal degeneration slow) mutation in 11 separate families with an arginine-to-tryptophan substitution with common ancestry, and 1 family with an arginine-to-glutamine transition.

PATIENTS

Screening for RDS gene mutations was performed in 400 subjects with autosomal dominant retinal degeneration. Twelve families were identified with a mutation in codon 172. Haplotype analysis was performed. Full ophthalmic evaluation was performed, including electrophysiologic and psychophysical investigation and imaging of autofluorescence using confocal laser scanning ophthalmoscopy.

RESULTS

Haplotype analysis demonstrated that the 11 families were ancestrally related. All 12 families showed a common phenotype of macular dysfunction, with the deficit increasing with age. Abnormally high autofluorescence predated loss of visual acuity or visual field changes. Pattern electroretinographic (PERG) findings were affected early in disease. There was high intrafamilial and interfamilial consistency of phenotype.

CONCLUSION

These families demonstrate a striking conformity of symptoms and signs.

CLINICAL RELEVANCE

In the codon 172 RDS mutation, unlike disease resulting from other RDS mutations, prediction of approximate age of onset and progression of visual deficit is possible. This should assist diagnosis and counseling.

Intrafamilial variation of phenotype in Stargardt macular dystrophy-Fundus flavimaculatus

PURPOSE

To evaluate the intrafamilial phenotypic variation in Stargardt macular dystrophy-Fundus flavimaculatus (SMD-FFM).

METHODS

Thirty-one siblings from 15 families with SMD-FFM were examined. Age of onset, visual acuity, and clinical features on fundus examination and fundus autofluorescence images, including presence or absence of central and peripheral atrophy and distribution of flecks, were recorded. In addition, electrophysiological studies were undertaken.

RESULTS

Large differences between siblings in age of onset (median, 12 years; range, 5-23 years) were observed in six of the 15 families studied, whereas in 9 families differences in age of onset between siblings were small (median, 1 year; range, 0-3 years). Visual acuity varied two or more lines among siblings in nine families. In 10 families (67%) siblings were found to have different clinical appearance on fundus examination and fundus autofluorescence images, whereas in 5 families (33%), affected siblings had similar clinical features. Electrodiagnostic tests were performed on affected members of 12 families and disclosed similar qualitative findings among siblings. In nine families there was loss of central function only; in two, global loss of cone function; and in one, global loss of cone and rod function.

CONCLUSIONS

In this series, although differences in age of onset, visual acuity, and fundus appearance were observed between siblings, electrophysiological studies demonstrated intrafamilial homogeneity in retinal function. The findings are difficult to reconcile with expression studies showing ABCR transcripts in rod photoreceptors but not in cones.

Difference between RP2 and RP3 phenotypes in X linked retinitis pigmentosa

AIM

X linked retinitis pigmentosa (XLRP) has two genetic loci known as "RP2" and "RP3". Clinical features reported to differentiate RP2 from RP3 include a higher prevalence of myopia and primary cone dysfunction in RP2, and late onset night blindness and tapetal reflex in RP3. Members from 14 XLRP families were examined in an attempt to verify these differences.

METHODS

16 affected males and 37 females from 14 XLRP families assigned as either RP2 or RP3 by haplotype analysis and/or by heterogeneity analysis were examined. Members of all 14 families who were willing to participate but unavailable for examination were contacted and detailed interviews carried out.

RESULTS

No clear phenotypic differences were found that could be used to reliably differentiate RP2 from RP3 with respect to myopia and onset of night blindness. The tapetal reflex was also found to be present in carriers of both RP2 and RP3.

CONCLUSIONS

XLRP is a heterogeneous class of rod degenerative disorders with no clear phenotypic differentiation between the two genetic loci RP2 and RP3. There is a continuum of clinical presentations which can be seen in both RP2 and RP3, but the features within a given family tend to be consistent. However, interfamilial variability is prevalent leading to a wide range of clinical presentations and more than one abnormal allele at each gene locus cannot be excluded.

Genetic analysis of the guanylate cyclase activator 1B (GUCA1B) gene in patients with autosomal dominant retinal dystrophies

The guanylate cyclase activator proteins (GCAP1 and GCAP2) are calcium binding proteins which by activating Ret-GC1 play a key role in the recovery phase of phototransduction. Recently a mutation in the GUCA1A gene (coding for GCAP1) mapping to the 6p21.1 region was described as causing cone dystrophy in a British family. In addition mutations in Ret-GC1 have been shown to cause Leber congenital amaurosis and cone-rod dystrophy. To determine whether GCAP2 is involved in dominant retinal degenerative diseases, the GCAP2 gene was screened in 400 unrelated subjects with autosomal dominant central and peripheral retinal dystrophies. A number of changes involving the intronic as well as the coding sequence were observed. In exon 1 a T to C nucleotide change was observed leaving the tyrosine residue 57 unchanged. In exon 3 a 1 bp intronic insertion, a single nucleotide substitution G to A in the intron 3' of this exon, and a GAG to GAT change at codon 155 were observed. This latter change results in a conservative change of glutamic acid to aspartic acid. In exon 4 a 7 bp intronic insertion, a single nucleotide A to G substitution in the intron 5' of this exon, and a single base pair change C to G in the intron 3' of exon 4 were seen. None of these changes would be expected to affect correct splicing of this gene. All these changes were observed in controls. The results of this study do not show any evidence so far that GCAP2 is involved in the pathogenesis of autosomal dominant retinal degeneration in this group of patients. All the changes detected were found to be sequence variations or polymorphisms and not disease causing.

Identification of novel RPGR (retinitis pigmentosa GTPase regulator) mutations in a subset of X-linked retinitis pigmentosa families segregating with the RP3 locus

The X-linked form of retinitis pigmentosa (XLRP) is a severe disease of the retina, characterised by night blindness and visual field constriction in a degenerative process, culminating with complete loss of sight within the third decade of life. Genetic mapping studies have identified two major loci for XLRP: RP3 (70%-75% of XLRP) and RP2 (20%-25% of XLRP). The RPGR (retinitis pigmentosa GTPase regulator) gene has been cloned within the RP3 genomic interval and it has been shown that 10%-20% of XLRP families have mutations in this gene. Here, we describe a single-strand conformational polymorphism-based mutation screening of RPGR in a pool of 29 XLRP families for which the disease segregates with the RP3 locus, in order to investigate the proportion of RP3 families with RPGR mutations and to relate the results to previous reports. Five different new mutations have been identified: two splice site mutations for exon 1 and three frameshift mutations in exons 7, 10 and 11. The percentage of RPGR mutations identified is 17% (5/29) in our genetically well-defined population. This figure is comparable to the percentage of RP2 gene mutations that we have detected in our entire XLRP patient pool (10%-15%). A correlation of RPGR mutations with phenotype in the families described in this study and the biochemical characterisation of reported mutations may provide insights into the function of the protein.

Fluorescein angiographic abnormalities after prophylactic macular photocoagulation for high-risk age-related maculopathy

PURPOSE

Initial studies suggest that drusen associated with age-related maculopathy resolve in response to laser photocoagulation; there are conflicting reports regarding whether this treatment might prevent neovascular complications and blindness. The goal of the Drusen Laser Study is to maintain good visual acuity in eyes at the highest risk for neovascular complications of age-related maculopathy. In this report, we alert the ophthalmic community to possible laser-induced complications in patients treated within the context of this clinical trial.

METHODS

A double-masked, randomized, controlled clinical trial of prophylactic macular photocoagulation for high-risk age-related maculopathy is in progress. Patients randomly assigned to treatment received a ring-type distribution of 12 light spots of argon laser photocoagulation. Drusen were treated directly only if they were present at the protocol treatment locations. Fluorescein angiography was performed in all patients at yearly review, and at nonprotocol visits if symptoms or clinical examination were suggestive of choroidal neovascularization.

RESULTS

Fluorescein angiographic abnormalities suggestive of choroidal neovascularization have been seen in treated eyes only: one patient in the pilot study and six patients in the Drusen Laser Study. No fluorescein angiographic abnormalities were seen in eyes of control subjects.

CONCLUSIONS

Laser photocoagulation in high-risk age-related maculopathy may induce choroidal neovascularization and, therefore, is not recommended outside the context of a randomized, controlled clinical trial.

A single EFEMP1 mutation associated with both Malattia Leventinese and Doyne honeycomb retinal dystrophy

Malattia Leventinese (ML) and Doyne honeycomb retinal dystrophy (DHRD) refer to two autosomal dominant diseases characterized by yellow-white deposits known as drusen that accumulate beneath the retinal pigment epithelium (RPE). Both loci were mapped to chromosome 2p16-21 (refs 5,6) and this genetic interval has been subsequently narrowed. The importance of these diseases is due in large part to their close phenotypic similarity to age-related macular degeneration (AMD), a disorder with a strong genetic component that accounts for approximately 50% of registered blindness in the Western world. Just as in ML and DHRD, the early hallmark of AMD is the presence of drusen. Here we use a combination of positional and candidate gene methods to identify a single non-conservative mutation (Arg345Trp) in the gene EFEMP1 (for EGF-containing fibrillin-like extracellular matrix protein 1) in all families studied. This change was not present in 477 control individuals or in 494 patients with age-related macular degeneration. Identification of this mutation may aid in the development of an animal model for drusen, as well as in the identification of other genes involved in human macular degeneration.

Repeated injections of a ciliary neurotrophic factor analogue leading to long-term photoreceptor survival in hereditary retinal degeneration

PURPOSE

To determine whether ciliary neurotrophic factor (CNTF) or brain-derived neurotrophic factor (BDNF) treatment leads to long-term photoreceptor survival in hereditary retinal degeneration.

METHODS

An autosomal dominant feline model of rod-cone dystrophy was used throughout the study with two normal animals. In the first experiment, intravitreal injections of a human CNTF analogue (Axokine; Regeneron Pharmaceuticals, Tarrytown, NY) were administered to one eye of each animal (n = 10) beginning on postnatal day 10 and were repeated every 4 weeks. Clinical and histopathologic examinations were performed at 5.5, 9.5, and 13.5 weeks. In the second experiment, animals (n = 17) were randomly assigned to receive intravitreal injections of either Axokine (at half the initial dose), human BDNF, or the vehicle for Axokine to one eye at 5.5 weeks. The same therapy was repeated every 4 weeks in each group. Clinical and histopathologic examinations were performed at 9.5, 13.5, and 17.5 weeks. Photoreceptor survival was assessed by cell counting. Apoptotic cells were identified by morphology and a modified TdT-dUTP terminal nick-end labeling (TUNEL) technique. In the third experiment, two normal animals were treated with Axokine as in the first experiment. Glial fibrillary acidic protein ((GFAP) immunohistochemistry was performed to assess glial cell reaction.

RESULTS

In the first two experiments, Axokine significantly prolonged photoreceptor survival (P < 0.01) and reduced the presence of apoptotic cells (P < 0.05) and TUNEL-positive cells (P < 0.05). In the second experiment, results in the the BDNF- and sham-injected eyes were not significantly different from those in the untreated eyes. Minimal posterior subcapsular cataract and mild retinal folds were found in all Axokine-treated eyes in both dystrophic and normal animals. These complications were milder in the second experiment when injections were started later and at a reduced dose. GFAP immunolabeling was also increased in all Axokine-treated eyes.

CONCLUSIONS

Axokine, but not BDNF, delays photoreceptor loss in this hereditary retinal degeneration. Repeated injections maintain the protective effect.

Reproducibility of fundus autofluorescence measurements obtained using a confocal scanning laser ophthalmoscope

AIM

To evaluate the reproducibility of the background fundus autofluorescence measurements obtained using a confocal scanning laser ophthalmoscope.

METHODS

10 normal volunteers and 10 patients with retinal disease were included in the study. One eye per subject was chosen randomly. Five images of the same eye of each individual were obtained, after pupillary dilatation, by two investigators using a confocal scanning laser ophthalmoscope. Background fundus autofluorescence was measured at 7 degrees temporal to the fovea in normal volunteers and between 7 and 15 degrees temporal to the fovea in patients. Within session reproducibility of the measurements obtained by each investigator and interobserver reproducibility were evaluated.

RESULTS

For investigator 1 the median values of fundus autofluorescence obtained were 31.9 units for normal volunteers and 27.3 units for patients. The median largest differences in readings in normal volunteers was 5.7 units (range 1.4-13.5 units) and in patients 4.2 units (1.5-15.1 units). For investigator 2 the median values of fundus autofluorescence obtained were 28.9 units for normal volunteers and 27.4 units for patients. The median largest difference in readings in normal volunteers was 3.6 units (2.7-11.7 units), and in patients 4.1 units (1.5-9.3 units). The median interobserver difference in readings in normal volunteers was 3.3 units and for patients 6.6 units. The median greatest interobserver difference in measurements obtained for normal volunteers was 8.8 units (8.4-23.0 units) and for patients 11.1 units (7.1-40.8 units).

CONCLUSION

Within session reproducibility of the measurements of background fundus autofluorescence was satisfactory. Although interobserver reproducibility was moderate, the variability of the measurements of fundus autofluorescence between observers appears to be small when compared with variation in fundus autofluorescence with age and disease.

A clinical and molecular genetic analysis of solitary ocular angioma

OBJECTIVES

To determine whether ocular angioma can occur in the absence of von Hippel Lindau (VHL) syndrome, to define the clinical characteristics of sporadic (non-VHL) angioma, and to estimate a prevalence for sporadic ocular angioma.

DESIGN AND PARTICIPANTS

A cross-sectional study of a cohort of patients with apparent sporadic ocular angiomatosis recruited from throughout the United Kingdom.

INTERVENTION

Clinical details and a family history were obtained for the patients in the cohort. Systematic ocular examination and further systemic screening were performed on the patients and relatives when possible. Leukocyte DNA was examined for VHL germline mutations.

MAIN OUTCOME MEASURES

Patients with solitary and typical VHL-like ocular angioma, without clinical and family histories for VHL, were selected as possible sporadic (non-VHL) ocular angioma cases. An estimate of the population prevalence of sporadic (non-VHL) ocular angioma was made from patients presenting in the East Anglian region of the United Kingdom over a 25-year period.

RESULTS

From 32 patients referred, 17 had typical solitary ocular angioma and no evidence of other VHL complications in themselves or in family members. All 17 patients were negative for germline VHL mutations. The mean age of presentation was 30.9 years (median, 27.5; range, 3-52); 11 of 17 eyes suffered visual loss and 4 of 17 tumors occurred on the optic disc. The estimated prevalence of non-VHL ocular angioma was 9.0 x 10(-6), 95% confidence interval (CI) = 3.3 - 19 x 10(-6) (1 in 110,000 persons, 95% CI = 1 in 53,000-300,000).

CONCLUSIONS

Sporadic ocular angioma can occur in the absence of VHL disease but appears less prevalently than VHL itself. The age of presentation, degree of visual morbidity, complications, morphology, and anatomic location of tumors are similar to those seen in VHL disease.

The relationships of age changes in retinal pigment epithelium and Bruch's membrane

PURPOSE

To study the correlations between age, Bruch's membrane (BM) thickness, retinal pigment epithelial (RPE) autofluorescence, and RPE residual body content.

METHODS

Eight-millimeter-diameter macular discs from 88 unpaired human eye bank eyes were obtained within 72 hours of death, fixed in 10% neutral buffered formalin, and hemisected horizontally. One portion of the macular disc was embedded in paraffin and stained with periodic acid-Schiff for the measurement of BM thickness. RPE autofluorescence measurements were performed on unstained, deparaffinized sections. A second portion of the macular disc was prepared for electron microscopy to evaluate RPE residual body content. Linear and polynomial regression techniques were used to investigate the correlations between age, BM thickness, RPE autofluorescence, and RPE residual body content.

RESULTS

Bruch's membrane thickness increased with age according to the linear model. RPE autofluorescence and RPE residual body content also increased with age, but the correlations were best approximated by a quadratic model. The correlations between RPE autofluorescence and residual body content and between BM thickness and RPE autofluorescence were best approximated by a linear regression model. There was considerable variation in these correlations between specimens and within the same age group.

CONCLUSIONS

Although the changes in RPE and Bruch's membrane increased with age and there was a direct correlation between changes in the two tissues, there was considerable variation within each age group and between specimens. This probably reflects the multifactorial nature of the process.

Ocular abnormalities in Alagille syndrome

OBJECTIVE

To assess the type and frequency of ocular abnormalities occurring in Alagille syndrome (AS) in a large group of affected patients and their parents and the potential pathogenetic role of fat-soluble vitamin deficiency.

DESIGN

Observational case series.

PARTICIPANTS

Twenty-two children with AS and 23 of their parents participated.

MAIN OUTCOME MEASURES

Participants underwent full ophthalmic examination, including refraction, orthoptic examination, keratometry, slit-lamp examination, and funduscopy. Corneal diameter measurement was performed in a subset of nine and fluorescein angiography in a subset of six. Serum levels of vitamins A and E and cholesterol were measured.

RESULTS

The most common ocular abnormalities in patients with AS were posterior embryotoxon (95%), iris abnormalities (45%), diffuse fundus hypopigmentation (57%, a previously unreported finding), speckling of the retinal pigment epithelium (33%), and optic disc anomalies (76%). Microcornea was not associated with large refractive errors, and visual acuity was not significantly affected by these ocular changes. Vitamin levels were normal. Ocular abnormalities including posterior embryotoxon, iris abnormalities, and optic disc or fundus pigmentary changes were detected in one parent in 36% of cases.

CONCLUSIONS

Alagille syndrome is associated with a characteristic group of ocular findings without apparent serious functional significance and probably unrelated to fat-soluble vitamin deficiency. Simple ophthalmic examination of children with neonatal cholestatic jaundice and their parents should allow early diagnosis of AS, eliminating the need for extensive and invasive investigations.

An immunohistochemical study of an autosomal dominant feline rod/cone dysplasia (Rdy cats)

An autosomal dominant, early onset feline model of rod/cone dysplasia has been described. The clinical features, light and electron microscopy, and the electrophysiology were documented. We have now examined in more detail the histopathological and immunohistochemical changes during the early phase of the disease using antibodies against opsin, synaptophysin, glial fibrillary acidic protein (GFAP) and an epithelial marker (MNF118). We have also demonstrated programmed cell death by a modified TUNEL (Terminal deoxynucleotidyl transferase, Uridine triphosphate, Nick End Labelling) technique. In the Rdy cats, there was significant photoreceptor degeneration between 5 and 17 weeks of age. The TUNEL-labeled cell and pyknotic cell counts in the outer nuclear layer peaked at around 9 weeks of age. Accumulation of opsin in the entire outer nuclear layer of the retina was noted with opsin-immunolabeled rod neurite sprouting. There was a reduction in synaptophysin immunoreactivity in the outer plexiform layer. The Muller cells were activated and expressed GFAP. No significant change of immunolabeling of MNF118 was found. These findings closely parallel those seen in human RP.

[Serous central chorioretinopathy. Acute autofluorescence of the pigment epithelium of the eye]

PURPOSE

The lack of histopathological material has placed limitations on our knowledge on lipofuscin in central serous chorioretinopathy (CSCR). This study was designed to document the pathological changes of the retinal pigment epithelium (RPE) in CSCR using in vivo recording of fundus autofluorescence.

METHODS

Fundus autofluorescence was documented in 62 eyes of 44 subjects with CSCR using a laser scanning ophthalmoscope (Zeiss, Oberkochen; excitation wavelength: 488 nm, barrier filter at 521 nm). Images were compared to the respective fundus appearance and fluorescein angiograms.

RESULTS

Neurososensory retinal detachments showed diffuse increased autofluorescence corresponding to the detached area. Long-standing lesions showed very irregular autofluorescence with regions greater and less than the background levels of autofluorescence.

CONCLUSION

Focal accumulation of autofluorescent material occurs at the level of the RPE in patients with CSCR, relating to variation in metabolic activity of the RPE. This technique may be useful in selecting patients for laser photocoagulation.

Refined genetic and physical positioning of the gene for Doyne honeycomb retinal dystrophy (DHRD)

Doyne honeycomb retinal dystrophy (DHRD) is a late-onset autosomal dominant disorder that causes degeneration of the retina and can lead to blindness. We have previously assigned DHRD to a 5-cM region of chromosome 2p16 between marker loci D2S2739 and D2S378. Using sequence-tagged sites (STSs), expressed sequence tags (ESTs) and polymorphic markers within the DHRD region, we have identified 18 yeast artificial chromosomes (YACs) encompassing the DHRD locus, spanning approximately 3 Mb. The YAC contig was constructed by STS content mapping of these YACs and incorporates 13 STSs, including four genes and six polymorphic marker loci. We also report the genetic mapping of two families with a dominant drusen phenotype to the DHRD locus, and genetic refinement of the disease locus to a critical interval flanked by microsatellite marker loci D2S2352 and D2S2251, a distance of approximately 700 kb. These studies exclude a number of candidate genes and provide a resource for construction of a transcriptional map of the region, as a prerequisite to identification of the DHRD disease-causing gene and genes for other diseases mapping in the region, such as Malattia leventinese and Carney complex.

Distribution of pigment epithelium autofluorescence in retinal disease state recorded in vivo and its change over time

BACKGROUND

Recently a technique of imaging the retinal pigment epithelium (RPE) has been developed that takes advantages of its intrinsic fluorescence derived from lipofuscin. The purpose of this study was to document the distribution of fundus autofluorescence in patients with various retinal diseases and its change over time.

METHODS

The intensity and spatial distribution of fundus autofluorescence was documented in 318 eyes from 159 patients with various retinal diseases using a confocal Laser Scanning Ophthalmoscope. Thirty patients with macular dystrophies and 30 with age-related macular disease underwent serial examinations over a period of 1-3 years in order to monitor the changes over time of fundus autofluorescence.

RESULTS

Absent autofluorescence corresponded well spatially with outer retinal atrophy in eyes with retinitis pigmentosa and rod-cone dystrophy. Abnormally high background autofluorescence was seen in the macular region in some patients with dominant and recessive retinitis pigmentosa and rod-cone dystrophies. In areas of macular edema fundus autofluorescence was abnormal. Fundus autofluorescence showed changes over time in most of the eyes with retinal diseases studied.

CONCLUSION

Fundus autofluorescence allows documentation of areas of photoreceptor cell loss in eyes with retinitis pigmentosa and rod-cone dystrophies. If abnormal high background autofluorescence in the surviving areas occurs only in some patients with retinitis pigmentosa, the technique may serve to distinguish the regional from the diffuse type of disease. Over time, fundus autofluorescence may demonstrate change or may remain stable.

Accumulation of tissue inhibitor of metalloproteinases-3 in human eyes with Sorsby's fundus dystrophy or retinitis pigmentosa

BACKGROUND/AIMS

Tissue inhibitor of metalloproteinases-3 (TIMP-3) is normally synthesised by the retinal pigment epithelium (RPE) and deposited in Bruch's membrane. Mutations in the TIMP3 gene cause Sorsby's fundus dystrophy (SFD), which is characterised by thickening of Bruch's membrane, choroidal neovascularisation, and photoreceptor degeneration. To elucidate the role of TIMP-3 in human retinal degenerative diseases, we immunolocalised TIMP-3 in eyes with SFD caused by the Ser-181-Cys TIMP3 gene mutation or retinitis pigmentosa (RP; not caused by TIMP3 mutations).

METHODS

Standard light microscopic immunocytochemistry, including antigen retrieval, was used to localise TIMP-3 in paraffin sections of human eyes: two with SFD, three with different genetic forms of RP, and two normal.

RESULTS

In the SFD eyes, the thickened Bruch's membrane was strongly TIMP-3 positive except where RPE cells had degenerated. Similarly, in the RP eyes, Bruch's membrane was TIMP-3 positive except where RPE cells were lost, consistent with ongoing RPE mediated turnover of TIMP-3 in this region. In areas of total photoreceptor loss, migrated RPE cells formed cuffs around blood vessels in the RP retinas. Thick, TIMP-3 positive extracellular matrix (ECM) deposits associated with the migrated RPE cells occluded some vascular lumina, correlating with the observed loss of inner retinal neurons in RP.

CONCLUSIONS

TIMP-3 is a component of the increased ECM sequestered in Bruch's membrane in SFD. Further information is needed on normal TIMP-3/ECM interactions in Bruch's membrane and the effect of mutant TIMP-3 on this process. The finding of TIMP-3 accumulations in retinas with RP not caused by TIMP-3 mutations emphasises the importance of ECM remodelling in normal and diseased human eyes.

Disturbance of sleep in blindness

PURPOSE

To determine the prevalence and severity of sleep disturbance in blind subjects and its relation to the form and duration of visual loss.

METHODS

Of 403 blind subjects (visual acuity of less than 20/200 or a visual field of less than 5 degrees) recruited for the study, 15 were excluded because of affective disorder as identified by Montgomery Asberg Depression Scale. The remaining 388 subjects and a comparison group of 44 normally sighted individuals underwent an interview, and the Pittsburgh Sleep Quality Index questionnaire was administered. Sleep disturbance was classified as mild, moderate, or severe.

RESULTS

Disturbance of sleep was recorded in 189 (48.7%) of the blind subjects. The prevalence was higher and the sleep disturbance was more severe in those with no perception of light than in those with light perception or better visual acuity. In the comparison group, four (9.1%) had mild sleep disturbance only. The differences between blind subjects and normally sighted individuals were highly significant (P < .001). The most common sleep-related problem among the blind subjects was interrupted sleep, followed by increased sleep latency, short sleep duration, and daytime naps. Among the blind subjects, no correlation was found between the extent of sleep disturbance and the duration and pattern of visual loss.

CONCLUSIONS

Blind subjects who retain light perception, as well as those with total loss of vision, have a high frequency of sleep disturbance, although disorder is more common and more severe in subjects with no light perception. Management of the sleep disturbance may improve the quality of life in the visually handicapped.

Treatment of pigment epithelial detachments due to age-related macular degeneration with intra-ocular C3F8 injection

PURPOSE

To flatten pigment epithelial detachments (PED) due to age-related macular degeneration in an attempt to visualize the underlying choroidal neovascularization by fluorescein angiography (FA) and reveal a treatment target.

METHODS

Nine patients with PED received intravitreal gas injections via the pars plana and postured face down. Fluorescein angiograms were obtained before and after gas injection. In two patients, retinal scotopic sensitivity was also measured.

RESULTS

Eight patients demonstrated change in the shape and size of the PED following gas injection. Four patients showed a better delineation of underlying structures on FA. Three patients had focal laser treatment to the newly visible choroidal neovascular complex, but this was successful in only one patient with flattening of the PED.

CONCLUSION

Pigment epithelial detachments can be modified by intravitreal gas injection in some patients, but this treatment did not have a major impact on overall outcome or management.

Phenotype of a British North Carolina macular dystrophy family linked to chromosome 6q

AIMS

To document the phenotype of an autosomal dominant macular dystrophy diagnosed as having North Carolina macular dystrophy (NCMD) in this British family, and to verify that the disease locus corresponds with that of MCDR1 on chromosome 6q.

METHODS

37 family members were examined and the phenotype characterised. DNA samples from the affected members, 19 unaffected and five spouses, were used to perform linkage analysis with six microsatellite marker loci situated within the MCDR1 region of chromosome 6q.

RESULTS

Every affected family member had lesions characteristic of NCMD, which developed early in life and usually remain stable thereafter. Although fundus changes are evident in the periphery, all tests revealed that functional loss is restricted to the macula. Some patients with large macular lesions had good visual acuity with fixation at the edge of the lesion at 5 degrees eccentricity. Significant linkage to the MCDR1 locus on chromosome 6q was obtained with three marker loci, with a maximum lod score of 5.9 (q = 0.00) obtained with D6S249.

CONCLUSION

This family has the typical phenotype NCMD, and the causative gene was linked to the disease locus (MCDR1) on chromosome 6q. Early onset and localisation of the disease to the central macula allow specialisation of eccentric retina in some eyes with resultant good visual acuity.