Randomised clinical trial of lensectomy versus lens aspiration and primary capsulotomy for children with bilateral cataract in south India.
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AIMS: The primary objective was to determine which surgical technique gave the best long term visual outcome for infants and young children with bilateral symmetrical cataract in south India. Secondary objectives were to assess complications and the need for further surgical intervention. METHODS: A randomised controlled clinical trial was undertaken. 65 children under 10 years old with bilateral cataract had one eye treated by lensectomy and the other by aspiration with primary capsulotomy. RESULTS: 56 children (86%) with a mean age at surgery of 53 months were reviewed 3 years after surgery. The overall binocular acuity was 6/18 or better in 57.1% and 6/60 or better in 94.6%. There was no difference in visual acuity between the matched pairs of eyes undergoing aspiration or lensectomy at the third year of follow up (p=0.57). Aspiration eyes were more likely to require a secondary procedure to restore vision than lensectomy eyes (66.1% v 1.8%). CONCLUSION: Aspiration with primary capsulotomy gives an acceptable visual outcome in this part of India providing that there is good follow up to manage capsule opacification. If secondary intervention is not possible owing to poor compliance with follow up, then lensectomy is likely to give better long term visual rehabilitation providing there is good maintenance and technical support for the lensectomy equipment. (+info)
Diabetic versus non-diabetic colour vision after cataract surgery.
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AIMS: To examine whether the colour vision abnormalities found in phakic patients with diabetes mellitus is preserved after removal of the lens by cataract surgery. METHODS: 21 diabetic (16 IDDM and five NIDDM) and 19 non-diabetic patients of comparable age, postoperative visual acuity, and sex distribution, all aphakic or pseudophakic following cataract surgery, had their monocular colour vision examined using the Farnsworth-Munsell 100 hue test. The fundus status of the diabetic patients ranged from no retinopathy to photocoagulation treated proliferative diabetic retinopathy. Patients with macular oedema were specifically excluded from the study. RESULTS: The error scores of both the diabetic (mean 146 (SD 94)) and the non-diabetic patients (83 (79)) did not deviate significantly from the age related normal range. The error score in the diabetic group was significantly higher than in the non-diabetic group (p=0.02) but the amplitude of the difference was small in comparison with previous studies of phakic subjects. The error scores in the diabetic group were not correlated with the degree of retinopathy (p>0.2). CONCLUSION: After cataract surgery only a minor difference exists between the colour vision scores of diabetic and non-diabetic patients. This indicates that accelerated yellowing of the lens in diabetes is the predominant cause of the colour vision anomaly found in phakic diabetic patients. (+info)
Deletion in the promoter region and altered expression of Pitx3 homeobox gene in aphakia mice.
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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. (+info)
Pitx3 is required for development of substantia nigra dopaminergic neurons.
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Dopaminergic (DA) neurons of substantia nigra in the midbrain control voluntary movement, and their degeneration is the cause of Parkinson's disease. The complete set of genes required to specifically determine the development of midbrain DA subgroups is not known yet. We report here that mice lacking the bicoid-related homeoprotein Pitx3 fail to develop DA neurons of the substantia nigra. Other mesencephalic DA neurons of the ventral tegmental area and retrorubral field are unaltered in their dopamine expression and histological organization. These data suggest that Pitx3-dependent gene expression is specifically required for the differentiation of DA progenitors within the mesencephalic DA system. (+info)
Pitx3 is required for motor activity and for survival of a subset of midbrain dopaminergic neurons.
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Mesencephalic dopaminergic (MesDA) neurons play crucial roles in motor and behavioral processes; their loss in Parkinson's disease (PD) results in striatal dopamine (DA) deficiency and hypokinetic movement disorder. The Pitx3 homeobox gene is expressed in the MesDA system. We now show that only a subset of MesDA neurons express Pitx3 and that in Pitx3-deficient aphakia mice, this subset is progressively lost by apoptosis during fetal (substantia nigra, SN) and postnatal (ventral tegmental area) development, resulting in very low striatal DA and akinesia. Similar to human PD, dorsal SN neurons (which are Pitx3 negative) are spared in mutant mice. Thus, Pitx3 defines a pathway for survival of neurons that are implicated in PD and that are required for spontaneous locomotor activity. (+info)
Early developmental failure of substantia nigra dopamine neurons in mice lacking the homeodomain gene Pitx3.
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The mesencephalic dopamine (mesDA) system is involved in the control of movement and behavior. The expression of Pitx3 in the brain is restricted to the mesDA system and the gene is induced relatively late, at E11.5, a time when tyrosine hydroxylase (Th) gene expression is initiated. We show here that, in the Pitx3-deficient aphakia (ak) mouse mutant, the mesDA system is malformed. Owing to the developmental failure of mesDA neurons in the lateral field of the midbrain, mesDA neurons are not found in the SNc and the projections to the caudate putamen are selectively lost. However, Pitx3 is expressed in all mesDA neurons in control animals. Therefore, mesDA neurons react specifically to the loss of Pitx3. Defects of motor control where not seen in the ak mice, suggesting that other neuronal systems compensate for the absence of the nigrostriatal pathway. However, an overall lower activity was observed. The results suggest that Pitx3 is specifically required for the formation of the SNc subfield at the onset of dopaminergic neuron differentiation. (+info)
Cataract surgical coverage and outcome in the Tibet Autonomous Region of China.
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BACKGROUND: A recently published, population based survey of the Tibet Autonomous Region (TAR) of China reported on low vision, blindness, and blinding conditions. This paper presents detailed findings from that survey regarding cataract, including prevalence, cataract surgical coverage, surgical outcome, and barriers to use of services. METHODS: The Tibet Eye Care Assessment (TECA) was a prevalence survey of people from randomly selected households from three of the seven provinces of the TAR (Lhoka, Nakchu, and Lingzhr), representing its three main environmental regions. The survey, conducted in 1999 and 2000, assessed visual acuity, cause of vision loss, and eye care services. RESULTS: Among the 15,900 people enumerated, 12,644 were examined (79.6%). Cataract prevalence was 5.2% and 13.8%, for the total population, and those over age 50, respectively. Cataract surgical coverage (vision <6/60) for people age 50 and older (85-90% of cataract blind) was 56% overall, 70% for men and 47% for women. The most common barriers to use of cataract surgical services were distance and cost. In the 216 eyes with cataract surgery, 60% were aphakic and 40% were pseudophakic. Pseudophakic surgery left 19% of eyes blind (<6/60) and an additional 20% of eyes with poor vision (6/24-6/60). Aphakic surgery left 24% of eyes blind and an additional 21% of eyes with poor vision. Even though more women remained blind than men, 28% versus 18% respectively, the different was not statistically significant (p = 0.25). CONCLUSIONS: Cataract surgical coverage was remarkably high despite the difficulty of providing services to such an isolated and sparse population. Cataract surgical outcome was poor for both aphakic and pseudophakic surgery. Two main priorities are improving cataract surgical quality and cataract surgical coverage, particularly for women. (+info)
Neonatal aphakia retards ocular growth and alters scleral gene expression in rhesus monkeys.
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PURPOSE: We hypothesize that remodeling of the scleral extracellular matrix, involving collagen and proteoglycan synthesis and turnover, is a key process involved in ocular growth. Decreased axial elongation is observed following neonatal removal of the crystalline lens in a rhesus monkey model of congenital cataract. We wanted to determine changes in gene expression in the operated and companion eye following lensectomy, especially for extracellular matrix in the sclera. METHODS: Between 4 and 7 days of age, infant monkeys underwent surgical removal of the lens from the right eye. Axial lengths of the operated and unmanipulated fellow eyes were measured and when interocular differences of >0.4 mm were achieved, monkeys were sacrificed and RNA was isolated from sclera. In order to determine changes in scleral gene expression in aphakic versus control eyes, we used Clontech's Atlas Gene Array (Human Cancer Array version 1.2) hybridized with total RNA from three monkeys. RESULTS: Atlas Gene Array analysis demonstrated differential expression of several genes in the operated versus the unmanipulated eye. Most notably, there was a statistically significant increase in expression of several extracellular matrix (ECM) genes including: aggrecan, decorin, biglycan, several collagens, and tenascin in the RNA from the sclera of the aphakic eyes when compared to the unmanipulated eyes. Genes for several matrix metalloproteinases (MMPs) showed no significant change following lens removal although there was a trend towards decreased expression. There were also statistically significant changes in the pattern of gene expression in the operated eye relative to the unmanipulated eye for cell adhesion, cell cycle, apoptosis, and cytoskeleton transcripts. CONCLUSIONS: Our results suggest that removal of the crystalline lens alters gene expression in the sclera with a prominent upregulation of ECM transcripts. These data support recent evidence that remodeling of the ECM composition of the sclera may be an important regulator of ocular growth. (+info)