Evidence for commonly used teaching, learning and assessment methods in contact lens clinical skills education.

INTRODUCTION: Evidence based practice is now an important part of healthcare education. The aim of this narrative literature review was to determine what evidence exists on the efficacy of commonly used teaching and learning and assessment methods in the realm of contact lens skills education (CLE) in order to provide insights into best practice. A summary of the global regulation and provision of postgraduate learning and continuing professional development in CLE is included. METHOD: An expert panel of educators was recruited and completed a literature review of current evidence of teaching and learning and assessment methods in healthcare training, with an emphasis on health care, general optometry and CLE. RESULTS: No direct evidence of benefit of teaching and learning and assessment methods in CLE were found. There was evidence for the benefit of some teaching and learning and assessment methods in other disciplines that could be transferable to CLE and could help students meet the intended learning outcomes. There was evidence that the following teaching and learning methods helped health-care and general optometry students meet the intended learning outcomes; clinical teaching and learning, flipped classrooms, clinical skills videos and clerkships. For assessment these methods were; essays, case presentations, objective structured clinical examinations, self-assessment and formative assessment. There was no evidence that the following teaching and learning methods helped health-care and general optometry students meet the intended learning outcomes; journal clubs and case discussions. Nor was any evidence found for the following assessment methods; multiple-choice questions, oral examinations, objective structured practical examinations, holistic assessment, and summative assessment. CONCLUSION: Investigation into the efficacy of common teaching and learning and assessment methods in CLE are required and would be beneficial for the entire community of contact lens educators, and other disciplines that wish to adapt this approach of evidence-based teaching.

Analyses on the distribution and influence of higher-order aberrations both clinically and experimentally among varied refractive errors.

PURPOSE: The aim of this work is to determine and compare the distribution and influence of higher-order aberrations (HOAs) both clinically and experimentally between different refractive errors. METHODS: Commercially available Shack-Hartmann aberrometer was employed to measure the HOA clinically in human eyes. Experimentally, HOA was measured in a model eye by simulating various refractive errors by constructing an aberrometer based on the same Shack Hartmann principle. One-way analyses of variance and simple regression were employed to analyze the distribution and influence of HOA among various refractive errors. RESULTS: A total of 100 eyes were clinically measured for aberrations, of which 35, 50, and 15 eyes were emmetropes, myopes, and hyperopes, respectively. Out of the total root mean square (RMS) value, the HOAs found in the human eyes were 23%, 7%, and 26% and in the model eye, it was 20%, 8%, and 10% between emmetropes, myopes, and hyperopes, respectively. The mean higher-order RMS was almost similar between the groups and among various refractive errors. There was no statistical significance between the individual Zernikes except for the coma in both human and model eyes. CONCLUSION: The mean HOA is similar amidst the different refractive errors. The presence of 23% HOA in emmetropes signifies that larger part of the human eye is capable of complying with HOA without compromising the image quality. This work signifies that HOA does not play an important role in image clarity for human eyes with regular refractive surface unlike irregular refractive surfaces.

Correlating Kane formula with existing intraocular lens formulae for corneal curvatures and axial lengths.

BACKGROUND: To evaluate the predictability of the Kane formula in estimating postoperative refractive outcome with various corneal curvatures and axial lengths (ALs) besides comparing with existing intraocular lens (IOL) formulae. MATERIALS AND METHODS: A prospective cross-sectional study was carried out among patients having uneventful cataract surgery at an eye hospital. A total of 50 eyes were considered for the study. The corresponding A-constant for the model of IOL implanted into the patient's eye was taken along with the actual power of IOL implanted and corresponding predicted power for the IOL power inserted were taken for all the chosen formulae and was termed as "Adjusted Predicted Refractive Power." This was compared with the actual refractive outcome and the absolute error (AE) was measured. The eyes were separated into groups in terms of corneal curvature as flat (<42D), medium (42D-46D), and steep (>46D) corneas. In terms of AL, it was grouped as short (≤22 mm), medium (>22.0-<24.0 mm), and long (>24.0 mm) eyes. RESULTS: The study included 50 eyes and the mean AE for all the selected formulae were calculated for each group. Over the entire corneal curvature range, none of the formulae showed any significance when compared with the Kane formula (P > 0.05). In short AL, SRK-T formula had a statistical significance over the Kane formula (P = 0.043), whereas no other group had any significance over the Kane formula in AL groups. CONCLUSION: The study shows, all formulae (SRK-T, Holladay1, Hoffer Q, Hill RBF, Barrett Universal II, Kane) are interchangeable to predict the IOL power for any of the corneal curvature and ALs.

A novel method in correcting aberropia using pin hole soft contact lenses: A case report.

Aberropia leads to decrease in image quality due to higher order aberrations (HOA). Correction of these HOA poses a great challenge to clinicians. A case report is presented here where a 30 year old male visited with complaints of cloudy vision, diplopia in reduced illumination along with inferior vertical elongation of light during night time in the right eye since 6 years. The unaided visual acuity was found to be 0.0 Log MAR units and near acuity was N6. The patient did not accept any correction in subjective refraction. The aberrometry findings revealed vertical trefoil and vertical coma of -0.33 µm and 0.53 µm in the right eye and -0.07 µm and 0.12 µm in the left eye. Orbscan revealed a difference of 30 µm and 25 µm between the anterior and posterior float for the right and left eye respectively. Due to the significant increase in irregular astigmatism, vertical coma and vertical trefoil in the right eye, rigid gas permeable lenses and Rose K lenses were tried, but the symptoms did not reduce. This was due to the increase in posterior corneal astigmatism as the posterior float was more than 25 µm in the right eye which led to a diagnosis of early keratoconus. As the decrease in pupil size reduces HOA, a pin hole (2.5 mm pupil) soft contact lens was tried which reduced the symptoms. Hence a novel method is proposed to eliminate HOA which corrects aberropia by using pin hole soft contact lenses.

Orthoptic parameters and asthenopic symptoms analysis after 3D viewing at varying distances / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To analyse visual modifications such as amplitude of accommodation, near point of convergence (NPC) reopsis and near phoria associated with asthenopic symptoms after 3D viewing at varying distances. METHODS: A prospective study. Thirty young adults were randomly selected. Each individual was exposed to 3D viewing thrice in a day for a fixed distance and the distance was varied on three consecutive days. Same video of equal duration and different screen sizes were used for every distance. Cyclic 3D mode of K-multimedia (KM) player was used for projecting the 3D video. Different variables like stereopsis, amplitude of accommodation, near point of accommodation, near phoria and asthenopic symptoms were recorded immediately after 3D video viewing. Stereopsis was measured with "Toegepast Natuurwetenschappelijk Onderzoek冶 or"Netherlands Organisation for Applied Scientific Research 冶 ( TNO test ), amplitude of accommodation and NPC were measured using RAF ruler, near phoria was measured using prism bar and a closed ended sample questionnaire was used to know the occurrence of asthenopic symptoms. Statistical analyses were performed using descriptive statistics, paired t-test etc. Qualitative data was analyzed using Chi-square test. RESULTS: For every distance of 40 cm, 3 m and 6 m, amplitude of accommodation was significantly reduced by 0.66 D,1.12 D and 1.44 D. NPC got significantly receded by 0.63 cm, 0.93 cm and 1.23 cm, and the near phoria was significantly increased by 0. 87, and 2. 2 prism dioptres (PD) base-in respectively. It was found that most of the subjects got pain around the eyes, headache and irritation for each viewing distance. This study also revealed that 3D video viewing in theaters may increase the symptoms of headache, watering and irritation. Symptoms like headache,watering,fatigue,irritation and nausea may increase considerably at home environment and symptoms such as headache and watering may cause significant discomfort by 3D viewing using a laptop. CONCLUSION: There was a significant difference in amplitude of accommodation, NPC, near phoria and asthenopic symptoms before and after viewing a 3D video and also at three viewing distances. There was a predominant occurrence of asthenopic symptoms after 3D video viewing at different distances.