Visual outcome of Soflens Daily Disposable and Soflens Daily Disposable for Astigmatism in subjects with low astigmatism

Purpose: To compare the visual outcome of Soflens Daily Disposables and Soflens Daily Disposable for Astigmatism (Bausch & Lomb, Rochester, NY, USA) when worn by subjects with low astigmatism. Methods: Forty‐one subjects (aged 19 to 40 years) with myopia between 0.50 D to 6.00 D and astigmatism not more than ‐1.25 D in at least one eye were recruited and fitted with spherical and toric soft contact lenses in this double‐masked, non‐dispensing cross‐over study. High and low contrast logMAR visual acuities were measured over the lenses. At the end of the study, each subject was asked to complete a questionnaire on vision, initial comfort and ease of handling of the two lens types. Results: Monocular and binocular high and low contrast logMAR visual acuities were significantly better with the toric lenses compared with the spherical lenses (p < 0.01). Results from the questionnaire showed a significantly higher grade for vision with the toric lenses than with the spherical lenses (p = 0.003) but no significant differences in initial comfort and ease of handling between spherical and toric lenses (p > 0.21). Conclusions: The results of the present study show that both subjective and objective vision in myopic subjects with low astigmatism improves significantly when corrected with toric lenses compared with spherical lenses.     

Corneal Response to Extended Wear of CAB Contact Lenses in Aphakia

We studied 41 aphakic eyes in 30 patients who had been wearing CAB (cellulose acetate butyrate) contact lenses on an extended basis. Patients were 51 to. 81 years old and averaged 14.3 months of wearing time. Visual acuity was very good. Pachometry measurements ranged from 0.42 mm to 0.66 mm and averaged 0.550 mm. This compares favorably with data in the literature on corneal thickness seen with routine use of PMMA or hydrogel lenses or with extended wear of hydrogel lenses. Corneal thickness was also compared with unoperated fellow eyes and eyes using CAB lenses on a daily basis only.     

Solving soft contact lens problems

Soft contact lens wearers encounter a variety of problems affecting their vision and comfort. Six patients with soft lens-related problems are discussed, illustrating the various sources of problems and approaches to their solution.     

Trends in Australian contact lens prescribing 2000

Background: This study was conducted to ascertain current modes of contact lens prescribing in Australia. Methods: One thousand questionnaires were randomly distributed to proportionate samples of optometrists in each state of Australia. The profession fits the majority of contact lenses in Australia and the sample represents 55 per cent of all optometrists. We requested details of the first 10 patients fitted with contact lenses after receipt of the questionnaire. Results: We received 224 completed questionnaires, detailing contact lens fits to 2,230 patients. The mean age of the patient group was 32.3 ± 12.9 years and 65 per cent of these were female. Sixty per cent of patients were existing wearers, the remainder being new fits. The data indicated that 94 per cent of new fits were with soft lenses, of which six per cent were for extended wear. For refits 83 per cent were soft lenses and 24 per cent were extended wear. It was clear that the lens of first choice was mid‐water‐content (52 per cent of all soft lens fits). Only nine per cent of all soft fits were for lenses which were not replaced on a planned basis. The majority of rigid lenses were prescribed using mid‐Dk materials (71 per cent). Analysis of solution prescribing indicates that multipurpose products were the most common regimens for planned replacement soft lenses. The percentage of hydrogen peroxide prescribed increased as lens replacement became less frequent. Conclusions: Non‐planned replacement lenses are now rarely prescribed to patients. Extended wear lenses and rigid lenses are prescribed more to existing contact lens wearers. The impact of multifocal lens designs on contact lens prescribing is very small, namely, five per cent of soft contact lenses and eight per cent of rigid lenses, despite 20 per cent of patients being over 45 years of age.     

Extended-wear lenses. An update

Extended-wear lenses present problems to be overcome by both the lens fitter and the patient. Guidelines are given for selecting patients and lenses, fitting the lenses, educating the patient, and handling complications. It is emphasized that patients who are happy with their day-wear lenses should not be urged to change to extended-wear lenses, and that if extended-wear lenses are worn, conscientious followup is crucial.     

The influence of lens conditioning on signs and symptoms with new hydrogel contact lenses

Background: Daily disposable contact lenses are considered to be the pinnacle of safe contact lens wear, yet it has been suggested that it takes some period of wear for the lens surface to reach optimal compatibility with the ocular surface. This study assesses the influence of brief treatment with a conditioning drop on the ocular response to new contact lenses over a single day of wear. Methods: The study was a single‐masked, paired (contralateral) comparison of the signs and symptoms with wear of new Acuvue 2 contact lenses pretreated with a conditioning agent containing carboxymethylcellulose (carmellose, CMC) against new lenses inserted directly from the blister pack. Sixty‐one subjects participated in the study, of whom 59 were considered eligible for data analysis. Subjects were also divided into symptomatic and asymptomatic lens wearers based on their overall comfort level in lens wear. Symptoms and signs were recorded at lens delivery and following eight hours of wear. Results: A set of slitlamp signs, comprising corneal staining (p < 0.05), limbal redness (p < 0.05), bulbar conjunctival hyperaemia (p < 0.05), bulbar conjunctival staining (p < 0.01) and palpebral conjunctival redness (p < 0.05) showed small but statistically significant (p < 0.05) end‐ofday mean values in favour of the lens that was conditioned with the rewetting agent. These data were supported by the proportion of subjects showing lower gradings with conditioned lenses versus unconditioned lenses, as follows: corneal staining (35 per cent versus 12 per cent, p <0.05), limbal redness (43 per cent versus 22 per cent, p < 0.05), bulbar conjunctival hyperaemia (50 per cent versus 15 per cent, p < 0.05), bulbar conjunctival staining (46 per cent versus 30 per cent, p < 0.1) and palpebral conjunctival hyperaemia (28 per cent versus 17 per cent, NS). For those subjects reporting symptoms with lens wear (n = 12), there was a statistically significant (p < 0.05) preference in terms of comfort as a result of preconditioning. Conclusions: The results of the investigation suggest that use of a conditioning agent can provide a more physiologically suitable environment for a new lens, thereby reducing the clinical signs associated with lens discomfort. The protocol used here, which is based on a statistical paradigm using standard pictorial grading scales, allows high sensitivity in detecting small changes in ocular parameters.     

Blepharoptosis in RGP and PMMA hard contact lens wearers

Background: Contact lens wear has been documented to cause an acquired non‐senile blepharoptosis. This is generally associated with prolonged wearing of hard contact lenses. The aim of this study was to determine the clinical features of blepharoptosis associated with contact lens wear including the type of contact lens and the duration of wear. Methods: This is a retrospective study of consecutive patients seen over four years (1997 to 2001) in the private practice of an oculoplastic surgeon. Results: A total of 15 consecutive patients presented over the four‐year period with blepharoptosis in the context of prolonged contact lens use. Four of the 15 patients (27 per cent) were wearing rigid gas permeable (RGP) lenses. The rest had been wearing PMMA hard lenses. Thirteen patients (87 per cent) had been wearing their contact lenses for more than 17 years. The patients' ages ranged between 15 and 71 years with a mean age of 46 years. All 15 patients had normal levator palpebrae superioris function. Four patients (27 per cent) had bilateral involvement. Eleven patients (73 per cent) underwent ptosis repair where aponeurosis thinning/dehiscence was noted. When compared with patients who presented over the same period with other causes of blepharoptosis (traumatic, myopathic, anophthalmic and involutional), contact lens wear was found to be an uncommon cause of ptosis across all age groups. Conclusion: The majority of contact lens wearers presenting with blepharoptosis gave a history of prolonged use of hard contact lenses. One explanation for this would be the mechanisms of removal of hard contact lenses. This involves pulling the lids laterally at the lateral canthus followed by a harsh blink, which over years can lead to levator aponeurosis dehiscence. Contact lens associated ptosis is an uncommon cause of acquired ptosis across all age groups.     

Corneal oedema during reverse piggyback scleral lens wear

Purpose

One clinical approach to address poor front surface wettability during scleral lens wear is the use of a “reverse piggyback” system (a soft contact lens applied to the anterior surface of a scleral lens). The aim of this study was to compare the magnitude of corneal oedema induced following short-term reverse piggyback scleral lens wear and standard scleral lens wear.

Methods

Ten young (mean age 22 ± 6 years) healthy participants with normal corneas were recruited. On separate days, central corneal thickness and fluid reservoir thickness were measured using optical coherence tomography before and after 90 min of standard scleral lens wear (Kerectasia Alignment Tangent Torus diagnostic lenses, hexafocon A, Dk 100 × 10⁻¹¹ (cm²/s)(ml O₂/ml × mmHg), Capricornia Contact Lenses, capcl.com.au ) and reverse piggyback scleral lens wear (the same scleral lens with a Dailies Total 1®, delefilcon A, Dk 140 × 10⁻¹¹ (cm²/s)(ml O₂/ml × mmHg), Alcon, alcon.com , applied to the anterior scleral lens surface).

Results

After correcting for small variations in the initial central fluid reservoir thickness, central corneal oedema was similar between the reverse piggyback (2.32 ± 1.15%) and standard scleral lens conditions (2.02 ± 0.76%; p = 0.45).

Conclusions

Following 90 min of lens wear, the highly oxygen-permeable reverse piggyback system did not induce a clinically or statistically greater magnitude of central corneal oedema compared with standard scleral lens wear in young adults with healthy corneas. This approach may be suitable to address poor front surface scleral lens wettability or to correct residual refractive error during diagnostic scleral lens fitting.     

Acanthamoeba keratitis and contact lens wear

Acanthamoeba keratitis is a rare but serious complication of contact lens wear that may cause severe visual loss. The clinical picture is usually characterised by severe pain, sometimes disproportionate to the signs, with an early superficial keratitis that is often misdiagnosed as herpes simplex virus (HSV) keratitis. Advanced stages of the infection are usually characterised by central corneal epithelial loss and marked stromal opacification with subsequent loss of vision. In this paper, six cases of contact lens‐related Acanthamoeba keratitis that occurred in Australia and New Zealand over a three‐year period are described. Three of the patients were disposable soft lens wearers, two were hybrid lens wearers and one was a rigid gas permeable lens wearer. For all six cases, the risk factors for Acanthamoeba keratitis were contact lens wear with inappropriate or ineffective lens maintenance and exposure of the contact lenses to tap or other sources of water. All six patients responded well to medical therapy that involved topical use of appropriate therapeutic agents, most commonly polyhexamethylene biguanide and propamidine isethionate, although two of the patients also subsequently underwent deep lamellar keratoplasty due to residual corneal surface irregularity and stromal scarring. Despite the significant advances that have been made in the medical therapy of Acanthamoeba keratitis over the past 10 years, prevention remains the best treatment and patients who wear contact lenses must be thoroughly educated about the proper use and care of the lenses. In particular, exposure of the contact lenses to tap water or other sources of water should be avoided.