Vision-Related Quality of Life after Cataract Surgery in West Africa.

PURPOSE: To study vision related quality of life (VRQoL) before and after a massive cataract campaign in West Africa and the relationship with visual indicators. METHODS: All the patients who received cataract surgery in Burkina Faso during a blindness prevention campaign were examined. VRQoL was assessed using a modified version of the WHO/PBD VF20. The questionnaire was changed to reflect the socioeconomic and local culture. Patients were interviewed by local interviewers before and three months after surgery. A quality of life related to vision index (QoL-RVI) was calculated. RESULTS: A total of 305 patients underwent cataract extraction in at least one eye, of these, a total of 196 (64%) completed the study. Mean age was 61.97 ± 14.39 years. The majority of eyes had poor visual acuity (VA<20/200, log MAR: 1.0) preoperatively (88.70%) with a mean VA of logMAR 2.17 ± 0.70 (20/2000) which improved to 0.86 ± 0.64 LogMAR (20/150) 3 months after cataract surgery. QoL-RVI improved postoperatively in 90.2% of patients, did not change in 3.1% and was worse in 6.7%. Statistically significant differences were detected (Wilcoxon test p <0.05) for all items tested before and after surgeries. Correlations for the patients after operations showed that there was a statistically significant relation between a global estimated QoL-RVI and the VA previous to the surgery (-0.196 p=0.014), regarding the same index and the VA after the procedures (-0,35 p=0,00018). CONCLUSION: Cataract surgery increases the quality of life of patients living in a developing country such as Burkina Faso and the improvement correlates with the recovery of the visual acuity.

OBJECTIF: Étudier la qualité de vie liée à la vision (VRQoL) avant et après une campagne massive contre la cataracte en Afrique de l'Ouest et la relation avec les indicateurs visuels. MÉTHODES: Tous les patients qui ont été opérés de la cataracte au Burkina Faso pendant une campagne de prévention de la cécité ont été examinés. La VRQoL a été évaluée en utilisant une version modifiée du VF20 de l'OMS/PBD. Le questionnaire a été modifié pour refléter la culture socio-économique et locale. Les patients ont été interrogés par des enquêteurs locaux avant et trois mois après la chirurgie. Un indice de qualité de vie liée à la vision (QoL-RVI) a été calculé. RÉSULTATS: Un total de 305 patients ont subi une extraction de la cataracte dans au moins un œil, parmi ceux-ci, un total de 196 (64%) ont terminé l'étude. L'âge moyen était de 61,97 ± 14,39 ans. La majorité des yeux avaient une mauvaise acuité visuelle (AV<20/200, logMAR : 1,0) en préopératoire (88,70%) avec une VA moyenne de logMAR 2,17 ± 0,70 (20/2000) qui s'est améliorée à 0,86±0,64 LogMAR (20/150) 3 mois après la chirurgie de la cataracte. La QoL-RVI s'est améliorée après l'opération chez 90,2% des patients, n'a pas changé chez 3,1% et s'est aggravée chez 6,7%. Des différences statistiquement significatives ont été détectées (test de Wilcoxon p <0,05) pour tous les éléments testés avant et après les opérations. Les corrélations pour les patients après les opérations ont montré qu'il y avait une relation statistiquement significative entre une estimation globale de la QoL-RVI et l'AV avant l'opération (-0,196 p=0,014), concernant le même indice et l'AV après les procédures (-0,35 p=0,00018). CONCLUSION: La chirurgie de la cataracte augmente la qualité de vie des patients vivant dans un pays en voie de développement comme le Burkina Faso et cette amélioration est corrélée avec la récupération de l'acuité visuelle. Mots clés: Qualité de Vie, Cataracte, Cécité, Afrique de l'Ouest.

There is more to accommodation of the eye than simply minimizing retinal blur.

Eyes of children and young adults change their optical power to focus nearby objects at the retina. But does accommodation function by trial and error to minimize blur and maximize contrast as is generally accepted? Three experiments in monocular and monochromatic vision were performed under two conditions while aberrations were being corrected. In the first condition, feedback was available to the eye from both optical vergence and optical blur. In the second, feedback was only available from target blur. Accommodation was less precise for the second condition, suggesting that it is more than a trial-and-error function. Optical vergence itself seems to be an important cue for accommodation.

Estimation of the mechanical properties of the eye through the study of its vibrational modes.

Measuring the eye's mechanical properties in vivo and with minimally invasive techniques can be the key for individualized solutions to a number of eye pathologies. The development of such techniques largely relies on a computational modelling of the eyeball and, it optimally requires the synergic interplay between experimentation and numerical simulation. In Astrophysics and Geophysics the remote measurement of structural properties of the systems of their realm is performed on the basis of (helio-)seismic techniques. As a biomechanical system, the eyeball possesses normal vibrational modes encompassing rich information about its structure and mechanical properties. However, the integral analysis of the eyeball vibrational modes has not been performed yet. Here we develop a new finite difference method to compute both the spheroidal and, specially, the toroidal eigenfrequencies of the human eye. Using this numerical model, we show that the vibrational eigenfrequencies of the human eye fall in the interval 100 Hz-10 MHz. We find that compressible vibrational modes may release a trace on high frequency changes of the intraocular pressure, while incompressible normal modes could be registered analyzing the scattering pattern that the motions of the vitreous humour leave on the retina. Existing contact lenses with embebed devices operating at high sampling frequency could be used to register the microfluctuations of the eyeball shape we obtain. We advance that an inverse problem to obtain the mechanical properties of a given eye (e.g., Young's modulus, Poisson ratio) measuring its normal frequencies is doable. These measurements can be done using non-invasive techniques, opening very interesting perspectives to estimate the mechanical properties of eyes in vivo. Future research might relate various ocular pathologies with anomalies in measured vibrational frequencies of the eye.

Optical power distribution of refractive and aspheric multifocal contact lenses: Effect of pupil size.

PURPOSE: To evaluate the power profile within the optic zone of different designs of multifocal contact lenses (CLs) and to analyze how the effect of pupil size could impact on their optical performance. METHODS: The optical power distribution within the optic zones of multifocal CLs was measured by the Nimo TR1504 (LAMBDA-X, Belgium). The multifocal CLs under study were the Acuvue Bifocal, the Acuvue Oasys for Presbyopia, the PureVision Multifocal and the PureVision 2 for Presbyopia. Each design was considered in all their available addition powers. All lenses had a nominal power of -3.0D. At the same time, three lenses of each model were considered and five consecutive readings of each lens were performed. RESULTS: The results show that the PureVision Multifocal and the PureVision 2 for Presbyopia have aspheric power profiles. Both designs showed aspheric center-near designs with a smoother progression of the optical power in the PureVision 2 for Presbyopia. The Acuvue Bifocal and the Acuvue Oasys for Presbyopia are shown to have concentric alternating near and far zones. Apart from the refractive rings, the Acuvue Oasys for Presbyopia showed an increase in negative (or less positive) values toward the periphery of the lens. CONCLUSIONS: Besides the refraction, the knowledge of the power profiles of multifocal CLs and the effect of pupil size on the optical distribution of these lenses could be crucial to understand the performance of these designs when they are fitted.

In vitro optical performance of a new aberration-free intraocular lens.

PURPOSE: To assess the optical performance of the new EnVista intraocular lens (IOL). MATERIALS AND METHODS: Four aspheric IOLs were evaluated; the new EnVista is one amoung them. This IOL, similarly to the Z-Flex HB and the Bi-Flex 1.8 667AB ones, has a neutral aspheric design, whereas the fourth IOL under test (AcrySof IQ IOL SN60WF) presents a negative spherical aberration (SA). The IOL's aberration patterns were measured in vitro, by setting them up on an optical bench. From these aberration-pattern data, the modulation transfer function (MTF), the average modulation values, and the points spread function (PSF) were calculated. Furthermore, in order to assess the potential optical quality that these IOLs would yield once they are implanted, an average corneal-aberration pattern was juxtaposed to the in-vitro profiles and the same parameters were calculated again. RESULTS: For the IOL-only scenario (ie, without including the corneal factor), it was the EnVista IOL, which is aberration-free that showed the higher MTF, PSF values. This was followed by the other two aberration-free IOL models. However, when the effect of an average corneal pattern was also taken into consideration, the AcrySof IQ IOL SN60WF always outperformed the other neutral-asphericity IOLs. CONCLUSIONS: The in-vitro optical performance of the EnVista IOL was good, but it decreases substantially in a whole-eye scenario, when the wavefront profile of an average cornea is added. Other designs with different degrees of SA should be considered for this IOL in order to surpass these results.

Comparison of visual and refractive results of Toric Implantable Collamer Lens with bioptics for myopic astigmatism.

PURPOSE: To compare visual and refractive results of Toric Implantable Collamer Lens (TICL) and bioptics (ICL plus excimer corneal surgery) to treat myopic astigmatism. METHODS: Eighty-one eyes underwent TICL implantation and 83 eyes were treated with bioptics (corneal ablation was performed between 1.5 and 6 months after ICL implantation). Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refraction, adverse events, safety, and efficacy were evaluated 12 months postoperatively. RESULTS: At 12 months postoperatively, the mean spherical equivalent was -0.15 ± 0.36 diopters (D) in the TICL group and -0.08 ± 0.26 D in the bioptics group (p = 0.099). Sixty-six (81.5 %) and 78 (94.0 %) eyes were within ±0.50 D for TICL and bioptics groups, respectively. The mean Snellen UDVA was not statistically different between both procedures (p = 0.909); 53 (65.4 %) and 54 (65.1 %) eyes achieved at least 20/25 or better in TICL and bioptics groups, respectively. No eye had lost more than two lines of CDVA, and 32.1 % of eyes (26/81) in the TICL group and 57.8 % of eyes (48/83) in the bioptics group had better postoperative UDVA than preoperative CDVA (p < 0.001). Safety was not statistically different between groups (p = 0.464) while efficacy was significantly higher in the bioptics group (p = 0.000). Two eyes with a TICL were treated to correct TICL decentration. CONCLUSIONS: Bioptics showed slightly better outcomes in some clinical measures such as uncorrected visual acuity, efficacy, and refractive predictability. TICL implantation shows reliable results similar to bioptics. A single procedure with TICL implantation might be preferred, eliminating the inherent risks of laser treatments and the risks of a second surgical procedure.

Long-term evaluation of the central vault after phakic Collamer® lens (ICL) implantation using OCT.

PURPOSE: The aim of this work is to evaluate the changes in the central vault after using implantable Collamer® lenses (ICL) to correct myopia. METHODS: This cohort study included 133 eyes; mean spherical equivalent -9.47 ± 3.71 diopters (D) (range: -2.75 to -22.25 D) who underwent ICL V4 implantation. Besides a complete ophthalmologic examination, the central vaulting was measured with Visante OCT and evaluated between different periods of follow-up (1 week, 1, 3, and 6 months, and yearly postoperatively). Post-operative time ranged from 6 to 73 months. RESULTS: Within the first 6 months, the mean central vaulting dropped from 510 ± 238 µm (range 100 to 940 µm) to 439 ± 231 µm (range 90 to 910) a significant decrease by 71 ± 58 µm (range -170 to 30 µm) (p = 0.028) with a trend to a lower reduction after this period. After 36 month from ICL implantation, this variation tends to be smaller with the majority of the eyes having a mean decrease smaller than 2 µm per month. Initial vault (Spearman Rho = -0.237, p = 0.006) was the factor more significantly associated with decrease in vault; eyes presenting a reduction in vault >100 µm had an average initial vault that was 141 µm and 184 µm higher than eyes with no change or with increase in vault over time, respectively. CONCLUSIONS: This study shows a continuous reduction of central vault over time. The reduction is highest during the first 6 months and tends to be lower and slow down over time. The decrease of vaulting was more pronounced in eyes with larger initial vaulting.

Performance of the compensation comparison method for retinal straylight measurement: effect of patient's age on repeatability.

AIM: The assessment of repeatability and reproducibility of retinal straylight measurements with the C-Quant straylight meter (Oculus AG, Germany) and the effect of patient's age on the instrument performance are tested with a series of experiments. METHODS: First, 20 eyes from 20 subjects (mean age 26.9 (SD 2.7) years, mean refractive error -1.34 (2.72) D) were examined with the C-Quant straylightmeter, taking 10 consecutive readings. Five subjects were also examined on five consecutive days to assess reproducibility. Additionally, repeated measures of straylight from 84 subjects of ages ranging from 19 to 86 years (mean (SD): 42.4 (24.0) years) were retrospectively analysed to assess the effect of patient's age on repeatability. RESULTS: The results failed to show significant differences between the readings taken within the same session (mean (0.07), p>0.05) or between sessions (mean (0.05), p>0.05). Variability of intrasession measurements was not significant for subjects of different age (p = 0.094). CONCLUSION: It may be concluded that the C-Quant straylightmeter is repeatable and reliable for the assessment of retinal straylight in human eyes. Age of the patient does not decrease repeatability, even though they feel more insecure about their ability to perform the test.

Technical note: a comparison of central and peripheral intraocular pressure using rebound tonometry.

PURPOSE: To compare central and peripheral intraocular pressure (IOP) readings obtained with rebound tonometry. METHODS: Intraocular pressure was measured on the right eye of 153 patients (65 males, 88 females), aged from 21 to 85 years (mean +/- S.D., 55.5 +/- 15.2 years) with the ICare rebound tonometer at centre, and 2 mm from the limbus (in the nasal and temporal regions along the 0-180 degrees corneal meridian). RESULTS: Intraocular pressure values obtained with the ICare were 14.9 +/- 2.8; 14.1 +/- 2.5 and 14.5 +/- 2.7 mmHg at centre, nasal and temporal corneal locations, respectively. On average, nasal and temporal IOP readings were 0.75 and 0.37 mmHg lower than the central reading (p < 0.05 and p > 0.05, respectively). A highly significant correlation was found between central and peripheral measurements in nasal (r(2) = 0.905; p < 0.001) and temporal (r(2) = 0.879; p < 0.001) regions along the horizontal meridian. Almost 80% of patients presented nasal IOP values within +/-1 mmHg of the central value. CONCLUSIONS: Intraocular pressure values measured with the ICare rebound tonometer on the nasal corneal region is slightly lower on average and highly correlated with IOP values recorded at corneal centre. Both nasal and temporal readings are in good agreement with central IOP, and could be used to obtain a reliable estimate of rebound IOP in corneas where central readings cannot be taken.

Age differences in central and peripheral intraocular pressure using a rebound tonometer.

AIM: To evaluate the influence of age on the measurements and relationships among central and peripheral intraocular pressure (IOP) readings taken with a rebound tonometer. METHODS: The IOPs were measured using the ICare rebound tonometer on the right eyes of 217 patients (88 men and 129 women) aged 18-85 years (mean 45.9 (SD 19.8) years), at the centre and at 2 mm from the nasal and temporal limbus along the horizontal meridian. Three age groups were established: young (< or =30 years old; n = 75), middle aged (31-60 years old; n = 77) and old patients (>60 years old; n = 65). RESULTS: A high correlation was found between the central and peripheral IOP readings, with the central readings being higher than the peripheral ones. Higher IOP values for the central location were found in the younger patients. Older patients had significantly lower temporal IOP readings than those for the remaining two groups (p<0.001), whereas no significant differences were found among groups when IOP was measured at the central and nasal locations. A significant decrease was observed in the nasal and temporal IOP readings as the age increased (p = 0.011 and 0.006, respectively). CONCLUSION: Older patients had lower IOP values than the middle-aged and younger patients in the temporal peripheral location. A negative correlation was found between age and IOP by rebound tonometry in the corneal periphery but not in its centre.

Influence of the luminance level on visual performance with a disposable soft cosmetic tinted contact lens.

The purpose of the present work was to study the effect on visual performance of wearing disposable soft tinted contact lenses for cosmetic purposes. Parameters such as contrast sensitivity (Vistech 6000), colour vision (Farnsworth-Munsell 100-Hue colour test), visual fields (static Goldmann perimetry) and subjective vision (what the wearer feels while wearing the lenses) were studied under different illumination levels in order to check for possible vision losses while wearing these contact lenses at low illumination levels. Sixteen emmetropic subjects were fitted consecutively with seven pairs of different colour lenses (Optima Colors lenses by Bausch & Lomb), and the experimental parameters were measured under four different illumination levels (60, 6, 1, and 0.1 cd/m2; but 15 and 0.3 cd/m2 for the static perimetry) The results obtained showed no statistically significant differences in visual performance between wearing the lenses and not wearing them (p > 0.01), except for the static perimetry, in which statistically significant differences (p < 0.01) occur at eccentricities greater than 30 degrees.

Intraocular pressure after excimer laser myopic refractive surgery.

The aim of this study was to determine whether intraocular pressure (IOP), as measured by Goldmann applanation or non-contact tonometry, shows systematic changes in patients who have undergone photorefractive keratectomy (PRK) or laser in situ keratomileusis (LASIK). IOP was measured by central Goldmann and non-contact tonometry in 54 patients pre and post-PRK, and in 43 patients pre- and post-LASIK. An interval of 12 months was allowed after surgery. Patients were selected to have one of four specific initial values of refractive error (-2.5, -5.0, -7.5 and -10.0 D). Fellow unoperated eyes were used as controls. A paired Student's t-test and a one-way ANOVA test were used for statistical analysis. After PRK and LASIK, a statistically significant decrease (p < 0.01) was observed in the IOP of the treated eyes (but not for control eyes; p > 0.01). Although the magnitude of the change increased with the attempted refractive correction, this trend was not statistically significant (p > 0.01). No statistically significant differences were found between the results obtained following the two types of surgery, although the recorded fall in IOP was smaller following LASIK (p > 0.01). The IOP measured after PRK and LASIK for myopia may be reduced because of reduced corneal thickness and curvature and, possibly, tissue softening after natural healing. The presence or absence of Bowman's membrane does not appear to be important in this context. The reduction in measured IOP following refractive surgery, by about 0.5 mmHg/D of myopic correction, needs to be remembered when possible abnormality of IOP in such patients is being considered.

Choice of spatial frequency for contrast sensitivity evaluation after corneal refractive surgery.

PURPOSE: To study the utility of measurements of contrast sensitivity at different spatial frequencies as an index of visual recovery following refractive surgery. METHODS: Contrast sensitivity at 1.5, 3, 6, 12, and 18 c/deg was measured with the Stereo Optical FACT chart in 20 patients after photorefractive keratectomy (PRK) using the Nidek EC-5000 excimer laser system, and in 18 patients following laser in situ keratomileusis (LASIK). Contrast sensitivity was measured preoperatively and 1, 3, 6, and 12 months after surgery. RESULTS: Results showed a statistically significant reduction (P<.01) in contrast sensitivity at all spatial frequencies in PRK patients during the first and third month, but contrast sensitivity recovered to preoperative values by 6 months after surgery (P>.1). In LASIK patients, decreased contrast sensitivity values 1 month after surgery were also obtained at all spatial frequencies. After 3 months, contrast sensitivity at 1.5 and 3 c/deg had recovered and did not differ significantly from preoperative values (P>.1), although contrast sensitivity at other frequencies remained reduced (P<.01). At 6 and 12 months, contrast sensitivity at all spatial frequencies did not differ from that obtained preoperatively (P>.1). CONCLUSIONS: Contrast sensitivity measurements at 6 and 12 c/deg appear to be most useful in the assessment of patients who have undergone laser refractive surgery because defocus and optical aberrations primarily affect the higher spatial frequencies.

Contrast sensitivity function in children: normalized notation for the assessment and diagnosis of diseases.

The purpose of this article is to describe a normalized notation for the assessment of the contrast sensitivity in children. This notation is obtained dividing the log contrast sensitivity value found in a patient by the corresponding normative contrast sensitivity data. The ratio obtained describes the contrast sensitivity of a patient facilitating its understanding, assessment and consequently effective communications. This article shows the normalized notation developed for children aged from 3 to 7 years old. An evaluation of the contrast sensitivity in healthy and amblyopic patients has been shown in order to explain the procedure to follow. The use of normalized notation in clinical procedures will provide to the clinician a better understanding of the results and the changes over time as well by comparison in the assessment of an ocular disease.

Latent ocular deviations in patients with advanced AIDS.

The purpose of this study is to determine horizontal latent ocular deviations in patients with advanced AIDS (CD4+ count <0.050 x 10(9)/l) and to compare with normal values by means of the von Graefe technique. Twenty patients aged between 17 and 44 years with AIDS and aged-matched control groups were submitted to study. The AC/A ratio was also measured in both groups using the Gradient test. The AIDS patients showed a horizontal latent deviation value of 0.28+/-1.07delta exo at near (40 cm.) and 2.12+/-1.37delta eso at distance (6 m). The AC/A ratio obtained was 2.03+/-0.65. Statistically significant differences were obtained in relation to aged-matched control group at near and at distance (p<0.01). The horizontal latent ocular deviation at near and at distance in advanced AIDS patients showed lower values than the expected. The AC/A relationship also was lower. The results obtained in this study indicate that AIDS patients suffer a divergence insufficiency, which could add to other visual complaints such as blurred vision, photophobia, nyctalopia and reading difficulty.

Distribution of refractive errors in Spain.

The aim of this work was to characterise the refractive state of a Spanish population. Special attention to myopia prevalence was carried out. At this stage 7621 subjects, 3692 males and 3929 females, between 3 and 93 years were examined by means of static retinoscopy and subjective refraction. The most prevalent was emmetropia with a mean percentage of 43.2% and ranging from 60.6% (3-8 years) to 29.0% (66-93 years). The prevalence of hyperopia (35.6%) increased with age, from 36.9% (3-8 years) to 55.8% (66-93 years). Myopia appeared to be more prevalent in the 30-35 age group (30.1%), agreeing with the more near-work demanding age range. Mean refractive error obtained was +0.19 +/- 3.42 D, ranging from +0.05 +/- 3.18 D (20-35 years) to +0.96 +/- 2.42 (66-93 years). Reading addition value obtained was similar to respective values of age of other populations. The whole Spanish population evaluated was emmetrop. No differences in prevalence from other populations were found, obtaining greater values of myopia in groups with more near work and a greater percentage of hyperopia versus age.

Eye-hand and eye-foot visual reaction times of young soccer players.

PURPOSE: The aim of this study was to investigate the eye-hand and eye-foot visual reaction time among young soccer players and to compare those with non-soccer players in order to evaluate possible differences. METHODS: A vision screening of 53 young male soccer players belonging to the Valencia Soccer Club was done. Soccer players were divided in three categories, with mean ages of 8.2 +/- 0.5 years (range, 8- to 9-year olds), 10.6 +/- 0.2 years (range, 10- to 11-year-olds), and 12.7 +/- 0.3 years (range, 12- to 13-year-olds). An age-matched sample of 60 young male non-soccer players served as a control population. Mean ages in this population were 8.3 +/- 0.6 years, 10.5 +/- 0.4 years, and 12.6 +/- 0.2 years for each category, respectively. Eye-hand and eye-foot visual reaction times were determined in players and non-players by means of a computer-controlled stimuli device. RESULTS: We obtained a mean and standard deviation value (in seconds) of eye-hand reaction time in soccer players of 0.301 +/- 0.037, 0.256 +/- 0.040, and 0.207 +/- 0.031, respectively, for each category, and for non-soccer players of 0.382 +/- 0.061, 0.320 +/- 0.063, and 0.282 +/- 0.043, respectively. The values for eye-foot reaction time in players were: 0.412 +/- 0.062, 0.406 +/- 0.046, and 0.387 +/- 0.034, respectively, for each category, and for nonplayers of 0.496 +/- 0.081, 0.460 +/- 0.026, and 0.446 +/- 0.054, respectively. There are statistically significant differences between eye-hand and eye-foot reaction times between players and nonplayers (p < 0.05). There was no correlation between visual reaction times and age (p > 0.05). CONCLUSIONS: Eye-hand and eye-foot visual reaction times were found to be different between the two populations evaluated. The results show differences between soccer and non-soccer players, with the soccer players demonstrating faster reaction times.

Astigmatism in infancy and childhood.

PURPOSE: To evaluate the prevalence of astigmatism in infancy and childhood in a Spanish population. METHODS: A total of 478 children with astigmatism from Valencia Province, Spain were examined. The patients, ranging in age from 2-12 years, were classified into groups according to age. Astigmatism error and axis orientation were determined using noncyclopegic retinoscopy over each eye. RESULTS: The overall prevalence of astigmatism (> or = 1.00 diopter of cylinder) decreased in relation to increasing age from 44.3% to 5.2%. The prevalence of against-the-rule astigmatism decreased from 61.5% (at 2 years) to 33.4% (at 12 years), with-the-rule astigmatism increased in prevalence from 23.1% (at 2 years) to 66.6% (at 12 years), and oblique astigmatism decreased with age from 15.4% (at 2 years) and 0% (at 12 years). CONCLUSION: These results do not vary from those observed in other populations. Factors such as race, nutrition, and environmental condition did not vary from the literature regarding the prevalence of astigmatism in infants and children.

Ocular physiology and artificial tears.

BACKGROUND: In this study, we evaluated the pH value of nine artificial tears solutions in order to investigate whether their pH changed over time. These solutions are designed to have a pH value within the ocular comfort range and to come close to the physiological tears' pH. METHODS: Fifteen bottles of each solution were randomly chosen from different production lots. Increments of 0.05 ml were taken daily from each bottle and measured daily, using a micropH 2002 Crison pH-meter over a period of 60 days. RESULTS: The values obtained fall within the ocular comfort range. Also, we obtained nonstatistically significant variations over time for each solution (p > 0.01). The results revealed differences between solutions, some solutions coming close to the tear's pH and others being slightly more acidic or alkaline. CONCLUSIONS: We may assume that all the solutions evaluated will not affect either the ocular physiology or the contact lens wear. The practitioners should know the properties of the solutions, thus selecting the adequate solution for each type of patient.

Antibacterial and antifungal effects of soft contact lens disinfection solutions.

AIMS: To study the antibacterial and antifungal effects of soft contact lens disinfection solutions. METHODS: Eight contact lens disinfection solutions containing hydrogen peroxide or biguanides or polyquad compounds were evaluated with respect to their ability to disinfect a saline solution experimentally contaminated with different bacteria and with a fungus. We used cultures in blood Agar, MuellerHinton agar and Saboureaud's agar to identify the bacterial and fungal growth following 14 h of exposure to the disinfection solutions. RESULTS: Hydrogen peroxide, DYMED and polyhexamide solutions prevented the growth of the four bacteria studied. The solution containing biguanide prevented the growth of Escherichia coli and Staphylococcus epidermidis. The solution with polyquad solution only prevented the growth of Staphylococcus epidermidis and none of the disinfection solutions prevented the growth of Candida albicans. The control solution, which was saline, did not prevent the growth of either bacteria or fungi. CONCLUSIONS: Disinfection solutions containing hydrogen peroxide, or DYMED or polyhexamide can disinfect these four bacteria but none of them prevented the growth of Candida albicans.