Central and Peripheral Ocular High-Order Aberrations and Their Relationship with Accommodation and Refractive Error: A Review.

High-order aberrations (HOAs) are optical defects that degrade the image quality. They change with factors such as pupil diameter, age, and accommodation. The changes in optical aberrations during accommodation are mainly due to lens shape and position changes. Primary spherical aberration (Z(4.0)) is closely related to accommodation and some studies suggested that it plays an important role in the control of accommodation. Furthermore, central and peripheral HOAs vary with refractive error and seem to influence eye growth and the onset and progression of myopia. The variations of central and peripheral HOAs during accommodation also appear to be different depending on the refractive error. Central and peripheral high-order aberrations are closely related to accommodation and influence the accuracy of the accommodative response and the progression of refractive errors, especially myopia.

Contrast sensitivity function with soft contact lens wear.

PURPOSES: To compare contrast sensitivity function (CSF) with soft contact lens (SCL) and spectacles wear. To investigate the effect of a three-month period of SCL wear on CSF. METHODS: Forty-seven myopic subjects with no history of contact lens (CL) wear were included in this longitudinal prospective study. CSF was measured with spectacles using the CSV-1000 (VectorVision, Greenvile, OH). Subsequently, subjects were fitted with a daily disposable lens (Nelfilcon-A, Stenofilcon-A or Nesofilcon-A) in one eye and a monthly disposable lens (Lotrafilcon-B, Comfilcon-A or Balafilcon-A) in the other eye and wore the same type of CLs for three months. CSF was measured again on the same day and after three months wearing CLs. Differences in CSF with spectacles and CLs on baseline and changes to CSF after three months of CLs wear were assessed. The effect of lens materials and wearing modality on CSF change was also investigated. RESULTS: CSF was higher with CLs in comparison to the values with spectacles for spatial frequencies of 3, 6 and 12 cycles per degree (cpd) (p<0.05) while there was no difference for spatial frequency of 18 cpd (p=0.114). No significant difference was found in the CSF with CLs between baseline and after three months of lens wear (p>0.05). There was no difference in CSF between hydrogel and silicone CLs as well as when comparing daily with monthly wear CLs (p>0.05). CONCLUSION: CSF is better with CLs than with spectacles. CSF values with CL are similar between baseline and after 3 months of lens wear.

Daily versus monthly disposable contact lens: Which is better for ocular surface physiology and comfort?

PURPOSE: To investigate the effect of soft contact lenses (SCL) wearing modality and lens materials on the changes in conjunctival bulbar and limbal redness and conjunctival and corneal staining after two months of SCL wear. Comfort level was also analyzed. METHODS: In this longitudinal clinical trial, forty-seven neophyte myopic subjects were fitted with a monthly disposable lens (lotrafilcon-B or comfilcon-A or balafilcon-A) in one eye and a daily disposable lens (nelfilcon-A or stenofilcon-A or nesofilcon-A) in the other eye, randomly selected. Conjunctival bulbar and limbal redness and conjunctival and corneal staining were evaluated before and after lens wear. Effect of lens wearing modality and lens materials on these changes was also determined. Level of comfort was evaluated subjectively twice per day. Comfort level and reduction in end-of-day comfort were compared between different lens wearing modalities and materials. RESULTS: Bulbar and limbal redness and conjunctival and corneal staining were increased (p<0.001) after lens wear, and changes were similar with daily and monthly disposable lens wear (p>0.05). Limbal redness was associated with lens materials, and lotrafilcon-B induced the least among the studied lenses (p<0.05). There was no significant association between the wearing modality and the average comfort level and reduction of end-of-day comfort (p>0.05). CONCLUSION: Two months of SCL wear increased conjunctival redness, conjunctival and corneal staining, which were not associated with the lens wearing modality. There was a reduction in end-of-day comfort, similar to daily and monthly lenses. The change in limbal redness and reduction in end-of-day comfort were associated with the characteristics of the lens material.

Causes of low vision and major low-vision devices prescribed in the low-vision clinic of Nepal Eye Hospital, Nepal.

Visual impairment is a major public health problem. Identifying the main causes of low vision and the major low-vision devices prescribed will help to develop and implement the low-vision rehabilitation service. We find out the causes of low vision and the low-vision devices prescribed in the low-vision clinic of Nepal Eye Hospital. A retrospective cross-sectional review of all patients attending the low-vision clinic from 1 May 2009 to 31 April 2011. Patients having visual acuity less than 3/60 in the better eye with best refractive correction were excluded. Of the 137 patients, the mean age was 32.53 ± 22.90 years; 71.5% were male and 67.88% were under 40. The major causes of low vision were nystagmus (30.70%), high refractive error (22.62%), cataract (15.30%), retinitis pigmentosa (15.30%) and age-related macular degeneration (13.10%); 78.10% patents were wearing glasses while telescopes were prescribed for 29.20% patients. Nystagmus, high refractive error and cataract are the main causes of low vision in Nepal. The majority of the low-vision patients seen in this clinic are of working age. Telescopes are the major low-vision device prescribed. We review approach the cause of low-vision problem in low-vision clinic Nepal Eye Hospital, Nepal.

Effect of three months of soft contact lens wear on conjunctival cytology.

BACKGROUND: The purpose of this study was to investigate the effect of three months of soft contact lens wear on conjunctival goblet cell density and epithelial cell morphology. METHODS: This was a longitudinal clinical trial. Conjunctival impression cytology was performed on the superior palpebral conjunctiva in fifty-four eyes of twenty-seven neophyte contact lens wearers before and after three months of contact lens wear. Goblet cell density was determined by optical microscopy and epithelial cell morphology was classified according to the Tseng classification. Changes in goblet cell density as well as epithelial cell grading were determined. The effects of lens material and wearing modality on cytological changes were also investigated. RESULTS: Goblet cell density reduced significantly by 85 ± 151 cells/mm(2) (p < 0.001) after three months of contact lens wear. Reduction in goblet cell density was associated with lens materials; it was higher in conventional hydrogel lenses in comparison to silicone-hydrogel lenses (p = 0.008). The highest reduction in goblet cell density was found with Nelfilcon A lens wear (p = 0.002) and the lowest with Comfilcon A lens wear (p = 0.414). There was no statistically significant difference in grading of epithelial metaplasia before and after three months of contact lens wear (p = 0.075). Age was not correlated with the reduction in goblet cell density (r = -0.196, p = 0.160) but it was associated with the change in epithelial cell morphology (p = 0.036). CONCLUSION: Three months of soft contact lens wear statistically significantly reduced goblet cell density; however, no significant changes were found in the grading of epithelial metaplasia. Contact lenses with lower oxygen permeability, higher Young modulus and higher thickness highly affected the conjunctival cytology.

Level of compliance in contact lens wearing medical doctors in Nepal.

PURPOSES: To determine the level of compliance and major non-compliant behaviors in contact lens (CL) wearing medical doctors (MDs) and to compare it with age matched CL wearing normal subjects with no medical background (NS). METHODS: Thirty-nine current CL wearing MDs, who were prescribed CLs in Nepal Eye Hospital, Kathmandu, Nepal, between 2007 and 2011, were interviewed on ten modifiable compliant behaviors regarding lens care and maintenance. The level of compliance and the rate of non-compliance for each behavior were determined and compared with NS. RESULTS: Level of compliance was good, average and poor in 35.9%, 48.7% and 15.4% of MDs, respectively. There was no significant difference in compliance between MDs and NS (p=0.209). Level of compliance was not associated with age, gender and duration of lens wear (p>0.05). Compliance rate varied according to different behaviors, achieving a good compliance level of 95% for hand hygiene, avoidance of water contact and not sleeping with lenses. There was poor compliance for topping up solution (53.8%) and lens case replacement (15.4%). CONCLUSION: About one third of MDs had a good level of compliance. Level of compliance and compliance rate of different behaviors were similar in MDs and NS. Periodic lens case replacement was the most neglected behavior in CL wearers for this region.

Contrast sensitivity function with soft contact lens wear / Función de sensibilidad al contraste con el uso de lentes de contacto blandas

PURPOSES: To compare contrast sensitivity function (CSF) with soft contact lens (SCL) and spectacles wear. To investigate the effect of a three-month period of SCL wear on CSF. METHODS: Forty-seven myopic subjects with no history of contact lens (CL) wear were included in this longitudinal prospective study. CSF was measured with spectacles using the CSV-1000 (VectorVision, Greenvile, OH). Subsequently, subjects were fitted with a daily disposable lens (Nelfilcon-A, Stenofilcon-A or Nesofilcon-A) in one eye and a monthly disposable lens (Lotrafilcon-B, Comfilcon-A or Balafilcon-A) in the other eye and wore the same type of CLs for three months. CSF was measured again on the same day and after three months wearing CLs. Differences in CSF with spectacles and CLs on baseline and changes to CSF after three months of CLs wear were assessed. The effect of lens materials and wearing modality on CSF change was also investigated. RESULTS: CSF was higher with CLs in comparison to the values with spectacles for spatial frequencies of 3, 6 and 12 cycles per degree (cpd) (p < 0.05) while there was no difference for spatial frequency of 18 cpd (p = 0.114). No significant difference was found in the CSF with CLs between baseline and after three months of lens wear (p > 0.05). There was no difference in CSF between hydrogel and silicone CLs as well as when comparing daily with monthly wear CLs (p > 0.05). CONCLUSIÓN: CSF is better with CLs than with spectacles. CSF values with CL are similar between baseline and after 3 months of lens wear

OBJETIVOS: Comparar la función de sensibilidad al contraste (CSF) con el uso de lentillas blandas y gafas. Investigar el efecto en la CSF de un periodo de uso de lentillas blandas de tres meses. MÉTODOS: En este estudio longitudinal prospectivo incluimos a cuarenta y siete sujetos miopes sin antecedentes de uso de lentillas. La CSF se midió con gafas, utilizando el sistema CSV-1000 (VectorVision, Greenvile, OH). A continuación, se proporcionaron a los sujetos lentillas diarias desechables (Nelfilcon-A, Stenofilcon-A o Nesofilcon-A) en un ojo, y lentillas mensuales desechables (Lotrafilcon-B, Comfilcon-A or Balafilcon-A) en el otro ojo, utilizándose el mismo tipo de lentillas durante tres meses. Se volvió a medir la CSF el mismo día, y transcurridos tres meses de uso de lentillas. Se evaluaron las diferencias en cuanto a CSF con gafas y lentillas al inicio, y los cambios de CSF transcurridos tres meses de uso de lentillas. También se investigó el efecto en el cambio de CSF de las modalidades de las lentillas y la modalidad de uso. RESULTADOS: La CSF fue más alta con el uso de lentillas, en comparación con el uso de gafas para las frecuencias espaciales de 3, 6 y 12 ciclos por grado (cpg) (p < 0,05), mientras que no se produjo diferencia para la frecuencia espacial de 18 cpg (p = 0,114). No se encontró diferencia significativa de CSF entre el valor basal y transcurridos tres meses de uso de lentillas (p > 0,05). No se encontró diferencia de CSF entre las lentillas de hidrogel y silicona, ni al comparar el uso de lentillas diarias y mensuales (p > 0,05). CONCLUSIÓN: La CSF es mejor con lentillas que con gafas. Los valores de CSF con el uso de lentillas son similares entre el valor basal y transcurridos tres meses de uso de lentillas

Goblet cell density association with tear function and ocular surface physiology.

PURPOSE: To determine the relationship of goblet cell density (GCD) with tear function and ocular surface physiology. METHODS: This was a cross-sectional study conducted in 35 asymptomatic subjects with mean age 23.8±3.6 years. Tear film assessment, conjunctiva and cornea examination were done in each subject. Conjunctival impression cytology was performed by applying Nitrocellulose Millipore MF™-Membrane filter over the superior bulbar conjunctiva. The filter paper was than fixed with 96% ethanol and stained with Periodic Acid Schiff, Hematoxylin and Eosin. GCD was determined by optical microscopy. Relation between GCD and Schirmer score, tear break-up time (TBUT), bulbar redness, limbal redness and corneal staining was determined. RESULTS: The mean GCD was 151±122 cells/mm(2). GCD was found higher in eyes with higher Schirmer score but it was not significant (p=0.75). There was a significant relationship of GCD with TBUT (p=0.042). GCD was not correlated with bulbar redness (p=0.126), and limbal redness (p=0.054) as well as corneal staining (p=0.079). No relationship of GCD with age and gender of the subjects (p>0.05) was observed. CONCLUSION: GCD was found correlated with TBUT but no significant correlation was found with the aqueous portion of the tear, limbal as well as bulbar redness and corneal staining.

Common symptoms of Nepalese soft contact lens wearers: A pilot study.

AIM: To determine the common symptoms in current soft contact lens (CL) wearers and their association with other factors among Nepalese population. METHODS: All the current CL wearers who started to wear soft CL in Nepal Eye Hospital between July 2007 and June 2012 were invited for the participation. Frequency of the ten most common symptoms, divided into never, occasionally, frequently and consistent were recorded. Association between degree of symptoms with other factors, e.g. age, gender, profession, cigarette smoking, ethnicity, level of education and duration and wearing modality of CL wear were analyzed. RESULTS: Out of 129 subjects participated in this study, 67% were female; the mean age of the subjects was 23.9±4.3 years. Ninety seven percent of them had at least one symptom occasionally or frequently or consistently. Discomfort was found in 88.4% of the total subjects. Other common symptoms were foreign body sensation in 73.6%, redness in 65.9%, reduced wearing time in 63.6% and dryness in 62.8%. Symptoms were found occasionally in the majority of subjects. Degree of symptoms was not associated with age, gender, profession, education status, ethnicity of subjects and duration or modality of lens wear (p>0.05) but was positively associated with passive cigarette smoking (p<0.001). CONCLUSION: Almost all of the Nepalese soft CL wearers had some types of symptoms at least occasionally. Discomfort was the most common symptom. Degree of symptoms was associated with the passive smoking but not with other factors like age, sex, profession and duration of lens wear.

A retrospective analysis of children with anisometropic amblyopia in Nepal.

PURPOSE: Anisometropia is one of the main causes of amblyopia. This study was conducted to investigate the association between the depth of amblyopia and the magnitude of anisometropia. METHODS: A retrospective record review was conducted at the Nepal Eye Hospital between July 2006 and June 2011. Those children included in this study were aged ≤13 years and diagnosed with unilateral anisometropic amblyopia, no strabismus and ocular pathology. Associations between the depth of amblyopia and the age and/or gender of the subjects, the laterality of the amblyopic eyes, the type and magnitude of refractive error of amblyopic eyes, and the magnitude of anisometropia were statistically analyzed. RESULTS: Out of the 189 children with unilateral anisometropic amblyopia (mean age 9.1 ± 2.8 years), 59% were boys. Amblyopia was more commonly found in left eye (p < 0.001). The most common type of refractive error was astigmatism (61%). The depth of amblyopia was not associated with the gender (p = 0.864) or age (p = 0.341) of the subjects or the laterality of the eyes (p = 0.159), but it was associated with the type (p = 0.049) and magnitude (p = 0.013) of refractive error of the amblyopic eye and the magnitude of anisometropia (p = 0.002). CONCLUSION: Nepalese anisometropic amblyopic children were presented late to hospital. The depth of amblyopia was highly associated with the type and magnitude of refractive error of the amblyopic eye and the magnitude of anisometropia. So, basic vision screening programs may help to find out the anisometropic children and reefer them to the hospital for timely management of anisometropic amblyopia if present.

Intraocular pressure measurement with ocular response analyzer over soft contact lens.

PURPOSE: To compare intraocular pressure (IOP) measured with ocular response analyzer (ORA) with and without soft contact lenses (CL) on eye. METHODS: Goldmann correlated intraocular pressure (IOPg) and corneal compensated intraocular pressure (IOPcc) were measured in 56 eyes of 28 subjects without any ocular pathology, using ORA. One eye was fitted with Narafilcon A (1-Day Acuvue True Eye, Johnson & Johnson) and the other eye with Nelfilcon A (Daily AquaComfort Plus, Ciba Vision), each with -3.00D and IOPg and IOPcc were again measured over CL. The variation in the IOP with and without CL was determined. RESULTS: Out of 28 subjects, 54% (15) were female. Mean age of the subjects was 29.4±9.8 years. Both the IOPg and IOPcc when measured with CL, were found statistically significantly lower than without CL (p<0.05). In subjects wearing Narafilcon A lens, IOPg and IOPcc were found 0.88±2.04mmHg and 1.55±2.16mmHg lower than without CL, respectively. Similarly, with Nelfilcon A lens, IOPg and IOPcc were found to be 1.03±1.93mmHg and 1.62±3.12mmHg lower, respectively. IOPcc was highly affected and underestimated by more than 3mmHg in upto 36% of the subjects. CONCLUSION: Measurement of IOP over minus (-3.00D) CL with ORA is dependent upon CL properties when measured in normal IOP population. It showed lower IOP over Narafilcon A and Nelfilcon A soft CL in comparison to the pressures measured without lenses. IOPg was found less affected by CL. For the accurate measurement of IOP with ORA, CL should be removed.

Microbial contamination of contact lens care accessories and compliance with care regimens in Nepal.

PURPOSE: To determine the rates of microbial contamination and identify contaminants associated with contact lens (CL) care accessories. To investigate self-reported compliance levels with care of CL accessories and its association with contamination level. METHODS: A total of 46 CL cases and care solutions from asymptomatic soft contact lens wearers were collected. Samples from the CL cases and care solutions were cultured for microbiological identification and enumeration. A questionnaire regarding compliance to care and hygiene procedures were administered to each subject on their visit. RESULTS: The percentage of microbial contamination for CL cases and care solutions was 50% and 10.9%, respectively. All the contaminants were bacterial. Staphylococcus aureus (37.0%, 17 of 46 cases) and Escherichia coli (8.7%, 4 of 46 cases) were the most common microorganisms detected in CL cases. In care solutions, S. aureus (8.7%, 4 of 46 samples), Pseudomonas aeruginosa (2.2%, 1 of 46 samples) were common contaminants. CL cases and care solutions that were used for <3 months were significantly less contaminated than those used for >3 months (10.9% versus 39.1%, p<0.05). Polyquad and Aldox based MPS solution showed no contamination. Subjects with medium or low compliance had highly significant rates of contaminations both in CL cases and solutions than for subjects with high compliance (p<0.05). CONCLUSIONS: Nepalese Soft CL wearers are at high risk of developing ocular complications due to high CL case and solution contamination. Frequent replacement of CL cases and solutions, as well as good compliance is recommended to reduce risk of contamination.

Ocular complications of soft contact lens wearers in a tertiary eye care centre of Nepal.

AIM: To determine the prevalence and the major types of ocular complications related with soft contact lenses (CL) in a tertiary eye care centre of Nepal. METHODS: Medical files of 4064 soft CL wearers who started wearing CL between January 2003 and December 2010 in BP Koirala Lions Centre for Ophthalmic Studies (BPKLCOS) Kathmandu, Nepal, were retrospectively reviewed. Records of patients who visited the hospital with complications were analyzed. Patients with ocular complications non-related with CL wear were excluded. RESULTS: Complications were found in 4.9% of the total soft CL wearers. Contact lens induced papillary conjunctivitis (CLPC) was the most common complication, comprising 36.9% of the total patients with complications. The other commonly found complications were superior punctuate keratitis (SPK) in 16.2%, conjunctivitis in 18.2%, meibomian gland dysfunction (MGD) in 8.6%, contact lens induced peripheral ulcer (CLPU) in 4%, corneal vascularization in 3.5% and microbial keratitis in 3%. The average time of first occurrence of complications after starting of contact lens wear was 14.3±11.4 months. CONCLUSION: CLPC, conjunctivitis and SPK were the most common types of soft CL related complications found in Nepal. Vision threatening complications like microbial keratitis was also found in some patients. Patient education in CL hygiene, after care schedule and frequent follow up examinations may help to minimize CL related complications.

Common symptoms of nepalese soft contact lens wearers: a pilot study / Síntomas comunes en los usuarios nepalís de lentes de contacto blandas: un estudio piloto

Aim: To determine the common symptoms in current soft contact lens (CL) wearers and their association with other factors among Nepalese population. Methods: All the current CL wearers who started to wear soft CL in Nepal Eye Hospital between July 2007 and June 2012 were invited for the participation. Frequency of the ten most common symptoms, divided into never, occasionally, frequently and consistent were recorded. Association between degree of symptoms with other factors, e.g. age, gender, profession, cigarette smoking, ethnicity, level of education and duration and wearing modality of CL wear were analyzed. Results: Out of 129 subjects participated in this study, 67% were female; the mean age of the subjects was 23.9 ± 4.3 years. Ninety seven percent of them had at least one symptom occasionally or frequently or consistently. Discomfort was found in 88.4% of the total subjects. Other common symptoms were foreign body sensation in 73.6%, redness in 65.9%, reduced wearing time in 63.6% and dryness in 62.8%. Symptoms were found occasionally in the majority of subjects. Degree of symptoms was not associated with age, gender, profession, education status, ethnicity of subjects and duration or modality of lens wear (p > 0.05) but was positively associated with passive cigarette smoking (p < 0.001). Conclusion: Almost all of the Nepalese soft CL wearers had some types of symptoms at least occasionally. Discomfort was the most common symptom. Degree of symptoms was associated with the passive smoking but not with other factors like age, sex, profession and duration of lens wear (AU)

Objetivo: Determinar los síntomas comunes en los usuarios actuales de lentes de contacto blandas (LC), así como su asociación a otros factores, entre la población nepalí. Métodos: Se solicitó la participación de los usuarios actuales de LC, que habían comenzado a utilizar dichas lentes en el Hospital Ocular de Nepal entre julio de 2007 y junio de 2012. Se registró la frecuencia de los diez síntomas más comunes, divididos entre: nunca, ocasionalmente, frecuentemente y consistentemente. También se analizó la asociación entre el grado de los síntomas y otros factores tales como edad, sexo, profesión, consumo de cigarrillos, etnia, nivel de educación, duración y modalidad de uso de LC. Resultados: De los 129 sujetos participantes en este estudio, el 67% eran mujeres; la edad media de los sujetos fue de 23,9 ± 4,3 años. El noventa y siete por ciento de ellos tenía al menos un síntoma de manera ocasional, frecuente, o consistente. El 88,4% de los sujetos reflejó malestar. Otros síntomas comunes fueron la sensación de cuerpo extraño en el 73,6% de los casos, el enrojecimiento en el 65,9%, la reducción del tiempo de uso en el 63,6%, y la sequedad en el 62,8%. Los síntomas fueron ocasionales en la mayoría de los sujetos. El grado de los síntomas no estuvo asociado a la edad, sexo, profesión, situación educativa, casta de los sujetos y duración o modalidad de uso de las lentes (p > 0,05), aunque se asoció de modo positivo a la exposición pasiva al humo del trabaco (p < 0,001). Conclusión: Casi todos los usuarios nepalís de LC blandas reflejaron algún tipo de síntoma, al menos ocasionalmente. El malestar fue el síntoma más común. El grado de los síntomas se asoció a la exposición pasiva al humo de tabaco, pero no a otros factores tales como edad, sexo, profesión y duración del uso de las lentes (AU)

Visual status of Nepalese national football and cricket players.

This study was undertaken to assess the visual acuity, refractive status, stereopsis, colour vision and ocular morbidity of Nepalese national footballers and cricketers. Ninety-five national football and cricket players of different age group, who had at least played one international tournament representing Nepal, were included in the study. A thorough ocular examination of the players was done in the study period of six months, which revealed that higher-level professional players have significant visual problems. Among the players 70.0% had never had complete ocular examination, 8.0% were found with refractive error, 60.0% with stereo acuity equal or less than 40" of arc and 65.0% with ocular complaints.