Contact Lens & Anterior Eye

Editorial Board

2010-02-01

Editorial

Shehzad A. Naroo — 2010-02-01

This time of year we look back at the year that has passed and make plans for the next year. I like to reflect on things that I have learnt and people that I have met, especially those who facilitated that learning. In 2009 I went to various conferences, The BCLA conference in Manchester, The Romanian Optical Society meeting in Brasov, Transylvania (where the university is actually on Vlad Tepes Street), The European Council for Optometry and Optics (ECOO) in Brno, Czech Republic, The American Academy of Optometry (AAO) in Orlando USA, The International Association of Contact Lens Educators (IACLE) meeting in Tianjin China and finally The Vereinigung Deutscher Contactlinsen-Spezialisten (VDCO) meeting in Jena. All were interesting places and thoroughly all were enjoyable conferences with their own highlights but I wanted to focus on Jena and one person I met there and his inspirational search for knowledge and the contributions he made in the field of contact lenses.

Dr. Norman Bier (1925–2009)

Richard Pearson — 2010-02-01

Norman Bier was born in Munich, Germany in 1925 and came to England shortly before the Second World War as a refugee from the Nazi regime. He studied optometry at the Northampton Polytechnic (now City University, London) and completed examinations to become a Fellow of the British Optical Association (BOA). He subsequently gained the Honours qualification of the BOA and Fellowship of the American Academy of Optometry.

The reproducibility of a new power mapping instrument based on the phase shifting schlieren method for the measurement of spherical and toric contact lenses

2009-12-21

Abstract: Purpose: To assess a new method of power measurement of soft and rigid contact lenses. The method is the phase shifting schlieren method, as embodied in the Nimo TR1504 instrument.Materials and methods: Three Nimo TR1504 instruments were used to measure the power related dimensions of: (a) a range of custom toric rigid lenses; (b) a range of commercially available spherical hydrogel lenses; and (c) a commercially available range of toric silicone hydrogel lenses. The measurements were carried out using a standard ISO ring test protocol where independent tests were carried out under conditions of reproducibility. The analysis of the measurements was carried out using ISO methods which enabled the reproducibility standard deviation, SR, of the method to be calculated.Results: The results show that this new method has SR of 0.048D for spherical soft (hydrogel) lenses. This means the back vertex power of spherical soft lenses having a power in the range ±10.0D can be determined to current ISO product tolerances with a single measurement. The method has SR of 0.059D for sphere power and 0.093D for cylinder power for toric soft lenses having powers in the range ±10.0D and cylinder powers in the range ±2.0D. A single measurement will determine sphere power to current ISO tolerance limits with 95% confidence while two measurements are required to determine the cylinder power to the same confidence level.

Lipophilic versus hydrodynamic modes of uptake and release by contact lenses of active entities used in multipurpose solutions

Charles H. Powell, John M. Lally, Lisa D. Hoong, Stanley W. Huth — 2009-12-25

Abstract: Purpose: To determine if the silicone-type components of new high Dk lens materials contribute significantly to uptake and/or release of two common antimicrobial agents, myristamidopropyl dimethylamine (Aldox) and poly[hexamethylene biguanide hydrochloride] (PHMB), found in multipurpose solutions.Methods: Five commercial contact lenses were cycled in lens cases in a PHMB- and an Aldox-containing MPS. Single-cycle soaks (6, 16 or 64h) and multi-cycle soaks (6, 16, 142 and 48h) were used to assess kinetics and saturation effects of uptake. Lens capacity for uptake of each entity was determined using a semi-saturation model. Release kinetics was assessed for these semi-saturated lenses (100-mL MPS-soaked) in 2mL of a tear mimic fluid.Results: Lenses that exhibited low uptake in a single cycle (with 3mL of MPS) became saturated within ∼3 cycles. PHMB uptake was highest with non-silicone hydrogel (non-SiHy) and/or ionic lenses (∼70% depletion in 16h). PHMB uptake by non-ionic SiHy lenses was low (<40% depletion in a single 3-mL soak of 64h). Aldox uptake was highest for all SiHy lenses (∼80% depletion in 16h).Conclusions: PHMB uptake capacity was highest by ionic and non-SiHy lenses, while Aldox uptake capacity was much higher with all SiHy lenses than with any non-SiHy lens. The slower desorption of PHMB (t1/2=∼120min) compared to Aldox (t1/2=∼20min) may partially explain observed higher staining after 2–4h with PHMB products used with some lenses, whereas any clinical effects from Aldox would be expected to manifest soon after insertion.

Demographic profile and visual rehabilitation of patients with keratoconus attending contact lens clinic at a tertiary eye care centre

Tarannum Fatima, Manisha Chhabra Acharya, Umang Mathur, Prasanjeet Barua — 2009-11-26

Abstract: Objective: To assess demographic profile and functional outcomes of patients with keratoconus attending contact lens clinic at a tertiary eye care centre.Materials and methods: Retrospective analysis of 77 patients (142 eyes) diagnosed with keratoconus attending contact lens clinic at Dr Shroff's Charity Eye Hospital, New Delhi, from January 2008 to December 2008 was done. Data on age, gender, slit lamp examination, keratometry, topography, visual acuity with log MAR conversion, degree of visual success, type of contact lens and fitting characteristics were obtained.Results: One hundred and forty-two eyes of 77 patients were analyzed of which 49 (63%) were males and 28 (37%) were females; their median age was 24 years (15–36 years). Keratoconus reading based on keratometry was done. Twenty eyes (14.4%) were diagnosed to have mild keratoconus, 51 eyes (36.7%) had moderate, 45(32.4%) had advanced and 23 eyes (16.6%) had severe keratoconus. 113 eyes (79.5%) were visually rehabilitated with RGP lenses while 29 eyes (20.4%) fitted best with Rose-K lenses and in 1 patient (0.1%) Boston scleral lens was given in both eyes. With contact lens wear, visual acuity improved to 6/9 (0.18log MAR) or better in 91% (115 eyes) and 141 (99%) eyes improved to 6/18 (0.48log MAR) or better.Conclusion: We found that in India keratoconus presents at an early age as compared to the western population. Contact lenses offer a good modality to delay the requirement for penetrating keratoplasty. Newer philosophies for fitting contact lenses and newer materials can help in decreasing the contact lenses intolerance which still remains the major indication for undergoing penetrating keratoplasty.

Toric lens orientation and visual acuity in non-standard conditions

Roberta McIlraith, Graeme Young, Chris Hunt — 2009-09-24

Abstract: Purpose: To evaluate and compare the effect of gravity and gaze direction on toric lens orientation and visual acuity (VA).Method: This was a 14 subject, randomised, unmasked, non-dispensing study, relating to the effect of gaze direction and posture on toric lens orientation and VA. Four lens types were assessed: Acuvue™ Oasys® for Astigmatism (AOfA), Purevision® Toric (PVT), Air Optix® for Astigmatism (AOT) and Proclear® Toric (PCT). In the first part of the study, subjects were positioned on their side and once lenses had settled, VA was measured and photographs taken of the lens orientation position. In the second part, the subjects were positioned at a slit-lamp and video-recordings taken as they changed from the primary gaze position to the eight cardinal directions of gaze.Results: In Part 1, all lenses rotated as a result of change in posture and head position. With subjects in a recumbent position mean rotation ranged from 11.0° with AOfA to 29.1° with PCT. The consequent mean reduction in VA ranged from 0.05logMAR for AOfA to 0.15logMAR for PVT and was significantly worse with PVT and PCT compared with AOfA (P<0.05). In Part 2, lenses tended to show inferio-nasal rotation on upgaze and inferio-nasal rotation on downgaze. The AOfA lenses showed less rotation on inferio-nasal version than each of the other designs (P<0.005). The AOT lenses showed significantly less rotation on superior-temporal version than PVT (P=0.01).Conclusion: Toric soft contact lens stability in extreme versions and postural positions can affect orientation and VA.

Demographics of international contact lens prescribing

2009-10-30

Abstract: Knowledge of differences in the demographics of contact lens prescribing between nations, and changes over time, can assist (a) the contact lens industry in developing and promoting various product types in different world regions, and (b) practitioners in understanding their prescribing habits in an international context. Data that we have gathered from annual contact lens fitting surveys conducted in Australia, Canada, Japan, the Netherlands, Norway, the UK and the USA between 2000 and 2008 reveal an ageing demographic, with Japan being the most youthful. The majority of fits are to females, with statistically significant differences between nations, ranging from 62 per cent of fits in Norway to 68 per cent in Japan. The small overall decline in the proportion of new fits, and commensurate increase in refits, over the survey period may indicate a growing rate of conversion of lens wearers to more advanced lens types, such as silicone hydrogels.

Corneal thinning associated with recurrent microbial keratitis resulting from 7-day extended wear of low Dk hydrogel contact lenses: A case report

Genís Cardona, Carlos Luís Saona-Santos — 2009-11-09

Abstract: Case description: Corneal thinning and an increased risk of corneal perforation, resulting from recurrent episodes of microbial keratitis, required a 38-year-old Caucasian female to undergo bilateral corneal grafting. Although strongly advised otherwise, the patient had been a long time user of low oxygen permeability hydrogel contact lenses in a flexible wear regime, with frequent overnight use.Discussion: Microbial keratitis is a potentially severe contact lens related complication which, if not properly treated, may lead to permanent visual loss. The introduction of silicone-hydrogel materials and daily replacement modalities has not resulted in a significant decrease in the incidence of microbial keratitis, thus suggesting that the condition is mainly dependent on patient hygiene and wearing habits. Non-compliance, which is endemic in contact lens wear, may be combated by increasing patient awareness of the potential risk factors of contact lens misuse. This is accomplished through constant, rigorous information provided by contact lens practitioners.

Confocal microscopy and optical coherence tomography imaging of hereditary granular dystrophy

Kristine Dalton, Simone Schneider, Luigina Sorbara, Lyndon Jones — 2009-11-30

Abstract: Objectives: This case report examines the clinical characteristics of hereditary granular dystrophy through the use of slit lamp digital photography, confocal microscopy (CM) and optical coherence tomography (OCT). A review of the literature describing the histopathological and genetic associations of stromal dystrophies, suggest it may be possible to differentiate dystrophies based on their clinical manifestations, and appearances of CM and OCT images, with or without the use of genetic testing.Case Report: Two sisters, previously diagnosed with Granular (Groenouw I) Dystrophy, were examined. Examination included the use of digital slit lamp photography, CM and OCT imaging.Results: “Breadcrumb” opacities were visualized in the anterior two-thirds of the stroma with all three imaging techniques. Opacities were demonstrated in the posterior third of the stroma with the digital photography and OCT techniques.Conclusions: The digital photography, CM and OCT images support the sister's diagnosis of Granular (Groenouw I) Dystrophy. Currently, genetic and histopathological testing are the only techniques available to determine exactly which corneal dystrophy and gene mutation are present. The results of this case report demonstrate that slit lamp digital photography, combined with CM and OCT may be capable of providing sufficient diagnostic information to diagnose corneal granular dystrophies in a clinical setting.

Keratoconus associated with the Pierre Robin Sequence

Ming-Lee Lin, Vishal Jhanji, Rasik B. Vajpayee — 2009-09-28

Abstract: A 30-year-old female with known Pierre Robin sequence presented to the emergency department of the Royal Victorian Eye and Ear Hospital, Melbourne, with acute unilateral hydrops as her first presentation of bilateral keratoconus. Initial management consisted of eye patching, hypertonic saline and cycloplegia. However, the long-term prognosis for visual rehabilitation remained poor in this patient because of the presence of a central corneal opacity and inability to comply with contact lenses. She was not an appropriate candidate for keratoplasty due to severe mental retardation. This report highlights an association of keratoconus in patients with the Pierre Robin sequence.

CET multiple choice questionnaire

2010-02-01

CET multiple choice answer sheet

2010-02-01

Acknowledgement of Reviewers 2009

2010-02-01