Soft contact lens parameter changes after using the lens2¨ automated lens cleaner machine

Disinfection of contact lens is an important procedure strongly emphasized by eye care practitioners. There are several types of disinfecting methods. Some methods have been proven to induce parameter changes on soft lenses. These parameter changes are likely to affect the efficacy of contact lens fitting and patients comfort. A self-controlled trial was carried out on a series of disposable soft contact lenses of different material to evaluate parameter changes after cleaning with Lens2¨ (Automated Lens Cleaner Machine). This will be compared to the lens cleaned conventionally (digital rubbing). Fifty four pieces of soft contact lenses were divided into 2 groups; cleaned conventionally and with Lens2¨. Three types of soft contact lenses of different materials were used; Soflens®38, Focus® Monthly and O2 Optix. Each contact lens was cleaned for 30 times to mimic the period of 30 days wear. After the thorough cleaning process, the back optic zone radius (BOZR), back vertex power (BVP), central thickness(ct) and total diameter (TD) were measured. The parameters were statistically analysed to evaluate the changes. There were significant changes in the TD and BVP of Soflens®38 and O2 Optix with both methods. The Focus® Monthly contact lens only showed significant BOZR changes with both methods. However, these parameter changes were not clinically significant because the changes were still in the tolerance range set by ISO (International Organization of Standardization). Both cleaning methods proved to maintain lens parameter within its acceptable range

Visual problems of new Malaysian drivers

Purpose: The objective of this study was to determine the prevalence of poor visual acuity, colour blindness and visual field defect of new Malaysian drivers. Methods: A total of 3717 new drivers (50.2% males and 49.8% females) age 19±6 years, voluntarily participated in this study. Standard optometric apparatus such as LogMAR Charts, Ishihara plates and HandHeld Bernell Perimeter were used and standard procedures were applied. Results: The visual examination showed 6.7% (n=250) of subjects achieved less than 0.3 LogMAR with better eye whilst 2.2% (n=83) had failed the Ishihara Test (2.1% males and 0.1% females). Most of the affected drivers were deutranopia. Only 2094 subjects had their visual field using a mobile Handheld Bernell Perimeter. 1.72% (n=36) subjects have less than 120 degrees of peripheral field of vision. Conclusions: The visual status among new Malaysian drivers needs to be taken seriously to ensure safe driving. Other factors such as colour vision and visual field screening have to be considered seriously when evaluating the visual performance of a driver. Good visual performance is indispensible for safe driving

Refractive surprise in post-cataract surgery in post Epi-LASIK patient : a lesson learnt

Post-myopic laser refractive surgery corneal power measurement for intraocular lens power calculation is one of the most challenging issues in cataract surgery. Standard keratometry measurement is likely to be overestimated which could lead to false-low intraocular lens power. As a result, this can lead to hyperopic surprise. Contact lens method is an alternative method which is relatively inexpensive and accessible procedure in many optometry and ophthalmology centres. The contact lens method with optimised equations have been used for this case to obtain an accurate postoperative corneal power

A Mobile Solution for Lateral Segment Photographed Images based Deep Keratoconus Screening Method

Keratoconus (KC) is a condition of the bulging of the eye cornea. It is a common non-inflammatory ocular disorder that affects mostly the younger populace below the age of 30.  The eye cornea bulges because of the conical displacement of either outwards or downwards. Such condition can greatly reduce one’s visual ability. Therefore, in this paper, we afford a mobile solution to mitigate the KC disorder using the state-of-the-art deep transfer learning method. We intend to use the pre-trained VGGNet-16 model and a conventional convolutional neural network to detect KC automatically. The experimental work uses a total of 4000 side view lateral segment photographed images (LSPIs) comprising 2000 of KC and non-KC or healthy each involving 125 subjects. The LSPIs were extracted from the video data captured using a smartphone. Fine tuning of three hyperparameters namely the learning rate (LR), batch size (BS) and epoch number (EN) were carried out during the training phase to generate the best model of which, the VGGNet-16 model fulfilled it. For the KC detection task, our proposed model achieves an accuracy of 95.75%, a sensitivity of 92.25%, and specificity of 99.25% using the LR, BS and EN of 0.0001, 16, and 70, respectively. These results confirmed the high potential of our proposed solution to apprehend KC prevalence towards an automated KC screening procedure

Accuracy of contact lens method by spherical and aspheric rigid gas permeable lenses on corneal power determination in normal eyes

Contact lens method (CLM) is an alternative option to measure corneal power by evaluating the difference of patient’s over-refraction with rigid gas permeable (RGP) lens to manifest refraction. The purpose of this study was to evaluate the accuracy of CLM using spherical (CLMspherical) and aspheric (CLMaspheric) RGP lenses in measuring corneal refractive power of normal corneas. This prospective study recruited 45 normal eyes of 45 healthy subjects. The corneal power measurements were determined by CLMspherical using Boston ES RGP and CLMaspheric using Boston Envision RGP based on alignment fitting strategy. Manifest refraction and over-refraction were determined using a standard procedure of objective and subjective refraction methods. IOLMaster was set as the reference method for comparison. The mean arithmetic difference, mean absolute difference and 95% limits of agreement (LOA) of corneal powers obtained from CLMspherical and CLMaspheric to IOLMaster value were evaluated for the accuracy assessment. The mean arithmetic difference and mean absolute difference of corneal power s obtained from CLMspherical and CLMaspheric to IOLMaster values were 0.10 ± 0.21 D and 0.20 ± 0.11 D, and 0.04 ± 0.09 D and 0.08 ± 0.05 D, respectively. The 95% LOA between CLMspherical and IOLMaster ranged from -0.30 to 0.51 D, whereas between CLMaspheric and IOLMaster was ranging from -0.14 to 0.21 D. CLM in estimating corneal power is more accurate with application of aspheric RGP compared to spherical RGP. Hence, aspheric RGP is suggested for CLM when determining corneal power in normal eyes

Comparison of driving difficulty between bilateral cataract and non-cataract patients among elderly drivers: a preliminary study

An age-related ocular disease such as cataract that causes reduction of visual functions would affect the individual driving performance. The aim of this study was to compare driving difficulties between Malaysian drivers with bilateral cataracts and without cataract. This cross-sectional study involved measurement of visual functions [visual acuity (VA) and contrast sensitivity (CS)] and driving difficulty of 61 subjects who are actively driving with valid driving license. Subjects were divided into bilateral cataract group (n=30) and non-cataracts group as control group (n=31); which age and gender matched. Results showed that the mean±SD for composite driving difficulty score in the bilateral cataract group and in the control group were 72.08±15.95 and 87.50±12.60 respectively. It showed that both groups had lower mean composite score which indicates difficulty in driving. Results also showed significant mean difference composite driving difficulty score between cataract and control group (p<0.001). Drivers with bilateral cataracts were also found to have significant difficulty when driving the rain (p=0.034), at night (p=0.013) and when driving on local or highway (p=0.005) compared to drivers without cataract. Subsequent Spearman’s Rho showed significant moderate positive correlation between driving difficulty and binocular CS (rs =0.404, p=0.027). This study showed that drivers with cataract would experience driving difficulties compared to the drivers without cataract

Pterygium classification using deep patch region-based anterior segment photographed images

Early pterygium screening is crucial to avoid blurred vision caused by cornea and pupil encroachment. However, medical assessment and conventional screening could be laborious and time-consuming to be implemented. This constraint seeks an advanced yet efficient automated pterygium screening to assist the current diagnostic method. Patch region-based anterior segment photographed images (ASPIs) focus the feature on a particular region of the pterygium growth. This work addresses the data limitation on deep neural network (DNN) processing with large-scale data requirements. It presents an automated pterygium classification of patch region-based ASPI using our previous re-establish network, “VggNet16-wbn”, the VggNet16, with the addition of batch normalisation layer after each convolutional layer. During an image pre-processing step, the pterygium and nonpterygium tissue are extracted from ASPI, followed by the generation of a single and three-by-three image patch region-based on the size of the 85×85 dataset. Data preparation with 10-fold cross-validation has been conducted to ensure the data are well generalised to minimise the probability of underfitting and overfitting problems. The proposed experimental work has successfully classified the pterygium tissue with more than 99% accuracy, sensitivity, specificity, and precision using appropriate hyperparameters values. This work could be used as a baseline framework for pterygium classification using limited data processing

Keratitis Acanthamoeba di Malaysia

Acanthamoeba spp. merupakan ameba hidup bebas yang tersebar luas di persekitaran. Ameba ini menyebabkan penyakit keratitis terutamanya kepada individu yang memakai kanta sentuh terkontaminasi atau mempunyai sejarah trauma pada mata. Tujuh puluh empat sampel kikisan kornea pesakit keratitis daripada 4 buah hospital di sekitar Lembah Kelang telah dikultur untuk menemukan Acanthamoeba spp. Keputusan kajian mendapati Acanthamoeba spp. berjaya dipencilkan daripada 14.87% sampel kikisan kornea pesakit keratitis. Berdasarkan kajian ini, kesemua pesakit keratitis Acanthamoeba adalah merupakan pemakai kanta sentuh yang majoritinya (90.9%) terdiri daripada kaum wanita. Kanta sentuh lembut terlibat dalam 90.9% kes manakala jenis kanta separa keras cuma satu kes 9.1%. Kesemua 11 pencilan Acanthamoeba yang dipencilkan adalah daripada kumpulan polyphagids yang biasanya patogenik kepada manusia dan menyebabkan jangkitan ini. Kegagalan pengguna kanta sentuh mengamalkan tahap kebersihan kanta sentuh yang baik merupakan faktor risiko yang penting dalam kejadian keratitis Acanthamoeba di Malaysia

Protein and microbial determinations on worn contact lenses cleaned conventionally using the Lens2® automatic lens cleaner

The accumulation of tear film proteins as well as microbes colonization onto worn contact lenses can be eliminated conventionally by mechanical rubbing during the cleaning process. Lens2® functions in rotation manner to loosen the deposits on the contact lens and has antimicrobial coating to keep lenses away from contamination. The objective of this study was to determine the efficiency of Lens2® to remove deposited protein and reduce microbial contamination compared to conventional method. Twenty-eight subjects each wore a pair of contact lens FDA Group 1 (Polymacon, SoftLens® 38, Bausch & Lomb) for one month and c l eaned them us ing mul t ipurpos e solut ion (COMPLETE ® MoisturePLUS TM , Advanced Medical Optics) separately using two different methods. The right lens was cleaned conventionally while the left lens were cleaned using the Lens2® The control group of thirteen subjects each . wore a pair of contact lens for the same period and cleaned both conventionally. These lenses and its cases were then analyzed for protein deposition using Bichinchoninic Acid Assay (BCA) Kit (Sigma, USA) in 96-well plate. Microbial contamination was determined by culturing the samples on nutrient agar for bacteria and fungi and non-nutrient agar for amoeba isolation. The mean of total protein on control lenses (17.014 ± 13.246 µg/mL) was not significantly different from those on the Lens2® (21.623 ± 19.127 µg/mL). There were also low growth numbers of amoeba in each group of samples. Interestingly, there were no growths of amoeba from all Lens2® samples collected. There was also low growth numbers of bacteria in each sample group whereby Lens2® had the lowest growth of bacteria. No growth of fungi was obtained from all samples. The automatic lens cleaner, Lens2® was found to be as efficient as the conventional cleaning method. However, the Lens2® has additional advantage Jurnal Sains Kesihatan Malaysia 6 (1) 2008: 11-2112 because of its antimicrobial material and need shorter time in the cleaning process as well as easy and effective

Punca infeksi Acanthamoeba spp. di kalangan pemakai kanta sentuh di Kuala Lumpur

The objective of this study was to determine the sources of the high incidence of Acanthamoeba infection among contact lens wearers in Kuala Lumpur. One hundred and seventy four samples were taken from 66 disposable soft contact lens wearers and they were also interviewed by using a questionnaire form. All the contact lens wearers used various types of disinfecting or multipurpose solutions to clean and disinfect their lenses. Swabs were taken from their worn contact lenses, lens storage cases and also from their remaining contact lens solutions. From these swaps a complete culture process was carried out toisolate the Acanthamoeba spp. The Acanthamoeba spp. was isolated successfully from 14 samples of 7 subjects. High yields of isolates were obtained from the lens storage cases (13.5%) and the contact lenses itself (10.6%). However, no isolation was observed from the disinfecting solutions used. The potential sources of Acanthamoeba infection were traced to the contact lenses and the lens storage cases. The oral questionnaires showed high percentage of incompliance among contact lens wearers where many used tap water for cleaning lenses and rinsing storage cases