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Myopia is constantly evolving, and this update focuses on comparing effectiveness of myopia control using different treatment methods, improving the level of control using orthokeratology (ortho-k), repeated low-density red light [...]

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The article discusses the benefits of orthokeratology while stressing the significance of thorough training of patients and parents. It explores the reduction in care and cleaning routine that possibly urged a more relaxed attitude to lens wear with patients who enjoy the privilege of fresh, safe lenses every day as long as they complied with the concept of daily disposables.

There has been increasing evidence of the emergence of antiseptic resistance mediated by quaternary ammonium compound (QAC) resistance genes, which may reduce the efficacy of disinfection. Although the presence of QAC-positive staphylococci has been shown to be elevated in contact lens wearers, the efficacy of multipurpose solutions (MPS) against such isolates has not been determined. This study investigated the efficacy of four MPS for rigid gas permeable (RGP) lenses against staphylococci-harbouring QAC genes.

To solicit parents’ knowledge on myopia control strategies available; to investigate their attitudes toward the use of orthokeratology (ortho-k), daily wear soft lenses, and spectacles for myopia control, assuming all three optical strategies were equally effective for myopia control; and to collect their opinion on the age at which children can commence contact lens wear for vision correction.

Acinetobacterhas low virulence but causes infections in subjects with reduced immunity. It has been reported in ocular infections including those of patients using contact lenses. Treatment is difficult because Acinetobacteris frequently multidrug resistant. Antibiotic-resistant strains frequently also harbor genes for antiseptic resistance (quaternary ammonium compound QAC) genes. Because Acinetobacteris part of the normal flora, it may contaminate contact lens and accessories. This study aims to investigate carriage rates of QAC genes in household and clinical isolates of Acinetobacterand to determine the effectiveness of two multipurpose solutions (MPSs) for soft lenses against organisms carrying QAC genes.

To investigate if the combination of partial reduction (PR) orthokeratology (ortho-k) and spectacles for residual refractive errors in the daytime was effective to slow myopic progression in high myopic children.

To determine the repeatability of relative peripheral refraction (RPR) measurements using an open-view automatic refractor in untreated and orthokeratology (ortho-k)-treated eyes of children.

To compare the rates of bacterial contamination in cylindrical and flat contact lens cases of orthokeratology (ortho-k) users and to investigate their preference of lens case design based on ease of use and handling.

To determine the efficacy of toric orthokeratology (ortho-k) in correcting myopia and astigmatism in myopic children with moderate to high astigmatism.

To investigate the effect of lens fenestrations on the performance of orthokeratology lenses.

The aim was to compare the thickness of each corneal sublayer and the visualization of superficial epithelial cells measured with the ConfoScan 4 (CS4) z-ring with and without the use of a soft contact lens and to evaluate the recovery rate of corneal staining after measurement with the CS4 (z-ring) with and without the application of artificial tears (ATs).

To compare the traditional manual hemacytometer method and an automated counter (Vi-cell) to enumerate and distinguish between viable and non-viable amoeba, and to determine the efficacies of contact lens (CL) disinfecting solutions against three species of Acanthamoeba. The efficacies in the presence of a bacterial food source and bovine serum albumin (BSA) were investigated.

This study investigated contamination of saline and daily disposable contact lens (DDCL) stored overnight after use in the original blister pack and the practices of a group of DDCL users.

To determine the repeatability of corneal sublayer thickness measurements using the Nidek ConfoScan 4 (CS4) with the z ring on a group of young adult subjects.

To compare the effects of drying the lens case with tissue on the presence of Acanthamoebawith cases left wet and to determine adherence to the lens case of varying concentrations of Acanthamoebasuspensions. The effect of drying on viability of Acanthamoebain new, used, and soiled lens cases was compared over a 24 h period.

Dry eye syndrome is a common age-related disorder, and decreased antioxidant/ultraviolet (UV) radiation protection in tears may be part of the cause. This study aimed to compare the tear antioxidant content and flow rate in young and older adults. The total antioxidant content and UV absorbing properties of various commercially available ophthalmic solutions used to alleviate dry eye symptoms were also examined.

To report the effect of stopping orthokeratology (ortho-k) lens wear on the changes in refractive errors and axial elongation in a girl who has been wearing ortho-k lenses for myopic control for over 2 years.

To investigate and compare changes in refractive astigmatism and corneal toricity in orthokeratology (ortho-k) using the Thibos vector analysis.

To determine the rates of microbial contamination of solutions and lens accessories of existing ortho-k lens wearers and the effect on contamination rates of monthly replacement and warnings. To investigate self-reported levels of compliance with care of the lenses and lens accessories and correlation of these levels with the rates of microbial contamination.

To determine and compare the cytotoxic effects on porcine corneal epithelial cells of commercially available multipurpose solutions (MPS) using fluorescein staining and flow cytometry (FCM).

To detect the presence of Acanthamoebain Hong Kong tap water and the contamination of contact lens cases using a polymerase chain reaction (PCR) method.

To simulate medium level “dry eye” and investigate the effect of “blink” rates in “dry eye” condition using a novel porcine dry eye model (pDEM).

To evaluate the refractive error and visual acuity (VA) at various contrast levels in the two eyes of overnight orthokeratology (ortho-k) subjects, and to compare their postortho-k VA with the best corrected VA of spectacle-wearing control subjects matched for age, gender, and initial refractive error.

Purpose: The aim of this survey was to evaluate the use of contact lenses, current prescribing habits of practitioners and the development of the contact lens market in Hong Kong.

Background: The aims of this study were to investigate the relative frequencies of correct identifications of variations in the fit of conventional rigid gas permeable (RGP) lenses and reverse geometry lenses (RGL) from fluorescein pattern analysis by orthokeratology (ortho‐k) practitioners and non‐ortho‐k practitioners and to determine whether fluorescein pattern analysis is sensitive for assessing ortho‐k lens fittings.

Background:This study investigated whether fresh main lacrimal gland secretion contains ascorbate, with a view to providing indirect evidence of an immediate source of this antioxidant in tears. Our hypothesis was that, if the source is corneal leakage, continuous tearing or rinsing of the eye will result in a marked decrease, by dilution, in ascorbate concentration in the reflex tears collected. Alternatively, the ascorbate concentration will be relatively constant if the main lacrimal gland secretion is the main immediate source.

Purpose:The aim of this study was to collect objective, subjective and demographic data on consecutively presenting orthokeratology (ortho‐k) patients who attended for routine followup examination in a Hong Kong based private practice in May 2001.

Purpose:The aim of the study was to provide information about the characteristics of three main types of orthokeratology (ortho‐k) lenses used in Hong Kong and to report on their performance based on the clinical impressions of a group of ortho‐k practitioners.

Purpose: To investigate the diurnal variation (daytime changes) of human tear protein levels, and to compare the results obtained by two sampling methods, the yawn and eye-flush methods.

Abstract: Background: It is known that the values of total protein concentration (TPC) of human tears obtained by different methods/standards vary considerably. The variations are due to differences in reactivity of proteins to the methods used. The aim of this study was to investigate the relationships and agreements between TPC values obtained by different methods/ standards. Methods: Two experiments were conducted. In experiment 1, 30 normal subjects were recruited and their TPC were determined by the Bradford and the modified Lowry methods, with bovine serum albumin and bovine immunoglobulin G as standards. The relationships (equations) between TPC values obtained by different methods/standards were determined. In experiment 2, another 15 normal subjects were recruited and the TPC were measured as in experiment 1. Measured values of TPC using different methods/standards were compared with their respective values calculated from the equations defined in experiment 1. The agreement and the reliability between the measured and the calculated values were investigated. Results: Experiment 1 showed that the TPC obtained by different methods/standards were strongly correlated to one another, and their relationships can be defined by linear equations. In experiment 2, the measured and the calculated values, using the equations defined in experiment 1, showed good agreement and reliability. This indicates that TPC obtained by one method/standard can be used to estimate the value(s) that would be obtained if another method/standard were used using the equation(s) found in experiment 1. Conclusion: The correlations between TPC values obtained by different methods/standards were strong. Our results also indicated good agreement and reliability between measured and calculated TPC values. Therefore, values obtained by different methods/standards are interchangeable using the appropriate equations.

Using a non-invasive tear break-up time (NITBUT) technique, we measured the tear stability of 22 asymptomatic Hong Kong (HK)-Chinese before and after performance of the phenol red thread (PRT) test. One eye was used as the test eye while the fellow eye acted as control. The effect of performing the PRT test before NITBUT measurements on NITBUT values was analysed by comparing the pre- and post PRT test NITBUT values of the test eye, and by comparing the post-PRT test NITBUT values of the test eye with the NITBUT values of the control eye. The median pre- and post-PRT test NITBUT values for the test eye were 129s and 10.4s, respectively; for the control eye, the NITBUT values were 17 7s and 14.7s, respectively. The mean±SD PRT value was 19.6±6.8mm/15s. PostPRT test NITBUT values may be longer or shorter than prePRT test NITBUT values. Similar findings were observed for the control eye between the first and second measurement. Performance of the PRT test before NITBUT measurement does not affect the NITBUT values of asymptomatic HK-Chinese. The performance of the PRT test in one eye also does not affect the NITBUT value of the fellow eye. The same procedures were repeated on 14 subjects using the fluorescein-instillation tear break-up time (TBUT) test instead of the NITBUT test. Performing the PRT test did not affect the TBUT values. The median pre- and post-PRT test TBUT values for the test eye were 3.8s and 4.2s, respectively,- for the control eye, the TBUT values were 5.4s and 4.1s, respectively. The mean±SD PRT value was 19.0±5.Omm/15s. The performance of the PRT test before NITBUT measurements does not appear to affect the locations of tear defects in the NITBUT test; the location of tear defects is not random but is most frequent in the inferior periphery of the cornea.

Tear volumes of 15 normal Hong Kong (HK-Chinese were measured using a cotton thread test (CM and the phenol red thread (PRT) test on 6 different days. The results showed that both CTT and PRT tests performed on normal subjects were reliable over time. The mean CTT and PRT values were 11.8 (±4.4)mm/15s and 15.4 (±4.9)mm/15s respectively. There is a significant difference between the CTT values and the PRT values so the two tests cannot be used interchangeably. There is a day-to-day variation in both tests which may be clinically significant for some subjects and we suggested that more than one measurement be taken when an accurate tear volume measurement is important for the management of the patient. We also compared our PRT results with those of previous investigators and found that the mean PRT value is significantly lower in HK-Chinese subjects than in Caucasian subjects, while no difference was found between HK-Chinese and Japanese subjects.

Introduction: A healthy corneal endothelium is essential for corneal transparency. The appearance of the corneal endothelium can be assessed quantitatively using the specular microscope combined with computer technology.Methods: Images of the corneal endothelium of 20 eyes from 12 subjects, who had normal ocular health, were captured and analysed using the Topcon SP‐1000, connected to the IMAGEnet system. Three methods of endothelial analysis (untreated, blocking and retracing) were used on each captured image. In the untreated method, the results of the analyses were automatically provided by the computer once the image was captured. For the blocking method, incorrectly traced or ill‐defined cells were blocked out by the operator manually and the endothelial variables were recalculated by the computer. For the retracing method, incorrectly traced cell borders were erased and reconstructed manually and the endothelial variables were recalculated.Results: The results obtained from the three methods of analysis were significantly different from each other (Repeated Measures Analysis of Variance, p < 0.05). Untreated results showed the highest coefficient of variation (mean ± SD: 60.1 ± 9.7 per cent) and endothelial cell density (3424.5 ± 227.7 cells/mm2) and the lowest hexagonality (38.8 ± 6.2 per cent). The results obtained using the retracing method show the lowest CV (30.2 ± 4.1 per cent) and ECD (2893.9 ± 257.2 cells/mm2) and the highest hexagonality (61.3 ± 11.4 per cent). CV. ECD and hexagonality using the blocking method were 34.0 ± 5.2 per cent, 3013.3 ± 240.8 cells/mm2and 48.5 ± 7.4 per cent, respectively.Conclusion: The method of retracing cell borders was more time‐consuming than when untreated data was used for analysis. Nevertheless, clinicians should consider using the retracing method of analysis since the results using untreated data provided by the IMAGEnet system were significantly different from the results using retraced data, and therefore were less accurate.

The authors investigated the effect of reading both Chinese and English articles on the non‐invasive tear film break‐up time and inter‐blink interval of 33 Hong Kong‐Chinese subjects. There were no significant differences in the non‐invasive tear break‐up time or the inter‐blink interval between reading a Chinese article and reading an English one. Reading had no effect on the non‐invasive tear break‐up time, but there was a significant increase in the inter‐blink interval when reading. Reduced blinking is a probable cause of symptoms of discomfort and gritty eyes during prolonged reading. There were significant correlations between non‐invasive tear break‐up time and inter‐blink interval before reading and when reading the Chinese article, but not when reading the English article. However, these results were due to one group of subjects only.

One hundred and ninety two patient files (for the year September 1995 – September 1996) from the Contact Lens Clinic of The Department of Optometry & Radiography, The Hong Kong Polytechnic University were surveyed. A total of 117 patients mostly using three lens care systems (CIBA VISION AOSept, Allergan Oxysept 1-step and Bausch & Lomb Multipurpose solution (MPS)) were included in this retrospective study of the incidence of corneal staining in patients using different lens care systems. The incidence and severity of staining observed was significantly higher and worse respectively in patients using MPS than in patients using the peroxide systems. Corneal staining was observed in 32.3% of the patients using AOSept, in 17.8% of the patients using Oxysept 1-step, and in 70.7% of the patients using MPS system. However, these percentages did not take into account other factors (which we assumed to be affecting the three groups equally) which may have caused some of the corneal staining observed. Of the patients who had corneal staining:u• 31% (9/29) of the patients using MPS system changed to peroxide system, and 38% (11/29) of the0838 1722V 2 patients were re-educated on proper lens care;• 77% (14/18) of the patients using the peroxide systems did not use proper care procedures.0838 1722V