In this article we provide an introduction to the use of likelihood ratios in clinical ophthalmology. Likelihood ratios permit the best use of clinical test results to establish diagnoses for the individual patient. Examples and step-by-step calculations demonstrate the estimation of pretest probability, pretest odds, and calculation of posttest odds and posttest probability using likelihood ratios. The benefits and limitations of this approach are discussed.

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Purpose: To evaluate the effects of onion juice on sodium-selenite induced cataract formation. Materials and Methods: Thirty-two 10-day-old Wistar-albino rat pups were divided into four equal groups. Group 1 received only subcutaneous saline injection. In Group 2, sodium-selenite (30 nmol / g body weight) was injected subcutaneously. In Group 3, subcutaneous sodium-selenite was injected and one drop 50% diluted fresh juice of crude onion was instilled every 8 h into the right eye for 14 days; the left eye received no treatment. Group 4 rats were similar to those of Group 3, the only difference being that of undiluted fresh juice of crude onion. The development of cataract was assessed. Rat lenses were analyzed for total antioxidant (TA) level, and for activities of glutathione peroxidase (GPX) and superoxide dismutase (SOD). Results: Both eyes of all rats in Group 1 did not exhibit cataract formation . In Group 2, all rats developed Grade 3 cataract in the lenses of both eyes. The difference in exhibited cataract in the lens of the right eyes in all rats between Group 2 and any eyes of groups 3 or 4 were significant ( P = 0.001). The mean TA level and mean activities of SOD and GPX in Group 2 rat lenses were significantly lower than the values in lenses of all rats in Group 1 ( P = 0.001, 0.003, 0.001), and in the lenses of the right eyes of rats in Groups 3 and 4 ( P = 0.001, 0.020, 0.001). Conclusion: Instillation of onion juice into the rat eyes can effectively prevent selenite-induced cataract formation. This effect was associated with increased TA level, SOD and GPX activities in the lens.

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Cataractous-opacification of the lens is one of the leading causes of blindness in India. The situation can be managed by surgical removal of the cataractous lens. Various pharmacological strategies have been proposed for the prevention and treatment of cataract. Information on possible benefits of putative anticataract agents comes from a variety of approaches, ranging from laboratory experiments, both in vitro and in vivo , to epidemiological studies in patients. This review deals with the various mechanisms, and possible pharmacological interventions for the prevention of cataract. The article also reviews research on potential anticataractous agents, including aldose reductase inhibitors, glutathione boosters, antiglycating agents, vitamins and various drugs from indigenous sources.

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We report the spectrum of ocular toxicity following accidental inoculation of latex of Calotropis procera (Sodom apple) in 29 eyes between January 2003 and December 2006. All patients presented with sudden painless dimness of vision with photophobia. Twenty-five (86%) patients had initial visual acuity of less than 20/60. All eyes had conjunctival congestion and mild to severe corneal edema with Descemet's folds. Three (10%) eyes had an epithelial defect, nine (31%) had iridocyclitis, and seven (24%) had associated secondary glaucoma. After treatment with topical corticosteroids, antiglaucoma agents, cycloplegics, hypertonic saline and tears supplements, 27 (93%) eyes recovered completely within 3-14 days. After three months, 17 (74%) out of 23 eyes showed a significant low endothelial cell count compared to the normal fellow eye ( P < 0.001). The latex of Calotropis procera causes significant ocular morbidity which may be preventable by simple health education. The long-term effect on corneal endothelium has to be studied further.

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Aim: To validate a system that uniformly and objectively assesses the risk of complications of cataract surgery performed with phacoemulsification technique in individual patients preoperatively. Materials and Methods: Outcome analysis of patient data entered into a standardized protocol. The data sheet was analyzed at a single center in terms of the risk assessed preoperatively and the incidence of surgical complications. This study did not assess the final visual outcome of eyes with complications. Each patient was categorized into a risk group according to the number of points scored. Group 1 (no added risk) 0 points, Group 2 (low risk) 1-2 points, Group 3 (moderate risk) 3-5 points, Group 4 (high risk) 6 points or more. Results: The number of eyes in each risk group was 2894 in Group 1 (44.1%), 1881 in Group 2 (28.6%), 1575 in Group 3 (23.9%), and 214 in Group 4 (3.3%). A total of 6564 eyes were assessed, of these 3669 eyes (55.9%) had a minimum of one risk factor and were thus not "routine". The group-specific events of complications were Group 1, 46 (1.6%), Group 2, 108 (5.7%), Group 3, 168 (10.7%), and Group 4, 69 (32.2%). The total incidence of complications was 5.7%. The group-specific rate of intraoperative complications increased through the risk groups ( P < 0.001). Conclusion: The study validates a scoring system that is predictive of intraoperative complications. This system uses information that is readily available from the preoperative history and assessment of the patient.

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A 32-year-old woman, three months pregnant, reported with the complaint of protrusion of the right eye for six months. She gave history of rapid protrusion of eyeball for the last two months along with the history of double vision for the last one month. Computer tomography (CT) scan revealed a well-defined mass lesion in the intraconal space of the right orbit which was excised through a lateral orbitotomy approach. Histological examination and immunohistochemistry revealed a solitary fibrous tumor, which showed a rapid progression in pregnancy.

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Late onset of corneal edema after cataract surgery is an unusual complication. We report a case of corneal edema presenting one month after cataract surgery. During implantation of the foldable lens, one haptic of the intraocular lens fractured at the optic haptic junction. This caused lens decentration, necessitating an intraocular lens exchange ten days later. The patient was recovering well but presented again two weeks later with a drop in vision due to corneal edema. A retained haptic of the intraocular lens was seen in the inferior anterior chamber angle. After surgical removal of the retained haptic the corneal edema fully resolved. Retained intraocular lens fragments can cause corneal endothelial damage, which may be reversible with an early diagnosis and intervention.

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We report a case of an 11-year-old boy who presented two days after blunt trauma to the left eye with a slingshot. On examination his best corrected visual acuity (BCVA) was 20/20 in the right eye and 20/400 in the left eye. Slit-lamp examination of the left eye revealed a Vossius ring, traumatic cataract, traumatic posterior capsule tear (PCT). The contour of the posterior capsule bulge corresponded to the edges of the PCT. Rotating Scheimpflug imaging (Pentacam 70700:Oculus, Wetzlar Germany) confirmed the traumatic cataract in the region of the PCT visualized as increased lens density at the cortex-vitreous interface. The extent of the PCT in the greatest and least dimensions was documented before and after intraocular lens (IOL) implantation. Intra-operatively, the PCT was evident and phaco-emulsification with an IOL implant was performed. Postoperatively, his BCVA improved to 20/20 in the left eye with a well-centered in-the-bag IOL as found on slit-lamp and Scheimpflug images.

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Aicardi syndrome is a rare genetic disorder. The salient features of this syndrome include agenesis of corpus callosum, chorioretinal lacunae and infantile spasms. Of these three, chorioretinal lacunae is the most constant feature present. This case highlights the importance of fundus findings by an ophthalmologist in making the diagnosis of this rare syndrome.

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Aim: Polymorphisms in γ-crystallins ( CRYG ) can serve as markers for lens differentiation and eye disorders leading to cataract. Several investigators have reported the presence of sequence variations within crystallin genes, with or without apparent effects on the function of the proteins both in mice and humans. Delineation of these polymorphic sites may explain the differences observed in the susceptibility to cataract observed among various ethnic groups. An easier Restriction Fragment Length Polymorphism (RFLP)-based method has been used to detect the frequency of four single nucleotide polymorphisms (SNPs) in CRYGA / CRYGB genes in control subjects of western Indian origin. Materials and Methods: A total of 137 healthy volunteers from western India were studied. Examination was performed to exclude volunteers with any ocular defects. Polymerase chain reaction (PCR)-RFLP based method was developed for genotyping of G198A (Intron A), T196C (Exon 3) of CRYGA and T47C (Promoter), G449T (Exon 2) of CRYGB genes. Results: The exonic SNPs in CRYGA and CRYGB were found to have an allele frequency 0.03 and 1.00 for ancestral allele respectively, while frequency of non-coding SNP in CRYGA was 0.72. Allele frequency of T90C of CRYGB varied significantly ( P = 0.02) among different age groups. An in-silico analysis reveals that this sequence variation in CRYGB promoter impacts the binding of two transcription factors, ACE2 (Member of CLB2 cluster) and Progesterone Receptor (PR) which may impact the expression of CRYGB gene. Conclusions: This study establishes baseline frequency data for four SNPs in CRYGA and CRYGB genes for future case control studies on the role of these SNPs in the genetic basis of cataract.

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Blind eyes can harbor a choroidal melanoma. We report a case of uveal melanoma presenting as staphyloma and complicated cataract in a 45-year-old female. The left eye was blind for six months. She underwent comprehensive ocular examination but fundus examination was precluded due to total cataract. The ultrasound of the eye showed a large mass filling the superior, nasal and inferonasal vitreous cavity with high surface reflectivity and low to moderate internal reflectivity. Magnetic resonance imaging (MRI) confirmed the diagnosis of choroidal melanoma. The patient underwent extended enucleation and histopathology was consistent with uveal melanoma.

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Visual functions of children with hearing disability were evaluated in a school of Muscat, Oman in 2006. Two hundred and twenty-three children were tested for near vision, distant vision, contrast sensitivity, color vision, field of vision, motion perception and crowding. Profound and severe hearing loss was noted in 161 and 63 students respectively. Thirty-five (81%) students with refractive error were using spectacles. Color vision and field of vision was defective in one student each. In 286 (64.1%) eyes, contrast sensitivity was defective. Abnormal contrast sensitivity was not associated with the severity of hearing loss [RR = 1.04 (95% CI 0.91 to 1.29)]. Children with hearing impairment should be assessed for visual functions. Refractive error and defect in contrast sensitivity were unusually high among these children. In addition to visual aids, we recommend environmental changes to improve illumination and contrast to improve the quality of life of such children with double disability.

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Aim: To compare the effects of balanced salt solution (BSS) and Ringer's lactate (RL) on corneal thickness, endothelial morphology, and postoperative anterior chamber inflammation in eyes undergoing phacoemulsification. Setting: Iladevi cataract and IOL research center, Ahmedabad, India. Materials and Methods: This prospective randomized study comprised 90 consecutive patients with age-related cataract who were randomly assigned to either Group 1 (n = 45) with BSS or Group 2 (n = 45) with RL. Observations made included measurement of central corneal thickness (CCT), presence of anterior chamber flare and cells, endothelial cell loss, and change in coefficient of variation (CV). Data was analyzed using Mann Whitney test and test of proportion. Results: Mean increase in CCT on postoperative Day 1 was 58µm and 97µm in Groups 1 and 2 respectively ( P = 0.01). Increase in CCT at one month was 10µm and 11µm in Groups 1 and 2 respectively ( P = 0.99); increase in CCT at three months was 3µm and 6µm in Groups 1 and 2 respectively ( P = 0.86). Number of eyes with flare grades in a range of 0 to 3 was statistically higher in Group 2 on postoperative Day 1 ( P = 0.004, 0.016, <0.001, 0.047 for Grade 0, 1, 2 and 3 respectively). Number of eyes with cells of Grade 3 on first postoperative day was significantly higher in Group 2 as compared to Group 1 ( P = 0.004). Three months postoperatively, endothelial cell loss was 5.5% and 7.8% in Groups 1 and 2 ( P = 0.21) and change in CV was 3 and 5.4 in Groups 1 and 2 ( P = 0.20) respectively. Conclusion: BSS offers a significant advantage over RL in terms of increase in corneal thickness and postoperative inflammation on the first postoperative day in patients undergoing phacoemulsification.

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Purpose: To assess accumulation of p53 protein in samples of primary pterygium from people living in two different climatic regions in Turkey. Materials and Methods: Group 1 included 101 pterygium specimens from people in Adana located in southern Turkey. Group 2 included 39 pterygium specimens from people in Ankara, located in the middle of Turkey. Climatic conditions throughout the year are sunnier and warmer in Adana than they are in Ankara. The control group (Group 3) included 30 specimens of conjunctiva that had been excised during cataract surgery from 30 patients without pterygium. The pterygial specimens and control conjunctiva were studied by immunohistochemistry using antibodies against p53 protein. Pearson's chi-square test was used to compare the p53 immunoreactivity. Results: The p53 immunoreactivity in Groups 1 and 2 was greater than it was in the control group ( P< 0.001). There were no differences in p53 immunoreactivity between Groups 1 and 2 ( P= 0.060). Conclusion: The p53 immunoreactivity was not correlated with ultraviolet irradiation exposure. The p53 immunoreactivity in our pterygium specimens suggests that pterygium could be a result of uncontrolled cell proliferation.

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We report a case of pulsating enophthalmos secondary to orbital varix associated with orbital bony defects. A 64-year-old female with pulsating enophthalmos of the right eye was found to have a right orbital mass with bony defects of the orbit. Valsalva maneuver failed to induce proptosis. The diagnosis of orbital varix was confirmed by exploratory orbitotomy. During general anesthesia for orbitotomy, proptosis of the right eye was noted. Ophthalmologists should be aware of the association between orbital varices and cranial bony defects and encephaloceles. Proptosis induced by general anesthesia and positive pressure ventilation suggests an underlying distensible venous anomaly.

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Purpose: The aim of this study was to compare the Humphrey MATRIX visual field (frequency doubling technology threshold) and Swedish interactive threshold algorithm (SITA) standard strategy white on white perimetry in detecting glaucomatous visual field loss. Material and Methods: Twenty-eight adult subjects, diagnosed to have glaucoma at a tertiary eye care hospital, who fulfilled the inclusion criteria, were included in this prospective study. All subjects underwent a complete ophthalmic examination. Subjects with glaucomatous optic disc changes underwent repeat perimetric examination on the same day with the Humphrey visual field analyzer (HFA II) and Humphrey MATRIX, the order of testing being random. Only reliable fields, where the HFA results corresponded to the disc changes were considered for analysis. A cumulative defect depth in each hemifield in both HFA and MATRIX reports was calculated. Results: Thirty-seven eyes of 24 subjects had reliable fields corresponding to optic disc changes. The mean age of the subjects was 56 ± 12 years. There were 12 males and 12 females. The test duration was significantly less on the MATRIX, mean difference in test duration was -81 ± 81.3 sec ( p < 0.001). The mean deviation and the pattern standard deviation between the two instruments showed no significant difference ( p = 0.55, p = 0.64 respectively) and a positive correlation coefficient of 0.63 and 0.72 respectively. Poor agreement was found with the glaucoma hemifield test. Conclusion: The Humphrey MATRIX takes less time in performing the test than SITA Standard and shows good correlation for mean deviation and pattern standard deviation. However, the glaucoma hemifield test showed poor agreement. The Humphrey MATRIX diagnoses were similar to established perimetric standards.

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