Change in refractive anisometropia in presbyopic adults wearing monovision contact lens correction.

BACKGROUND: Researchers studying the refractive development of infant monkeys suggest that monocular refractive error changes in response to induced ametropia; specifically, slightly blurring one eye may cause a difference to develop between each eye's correction (anisometropia) when none existed before wearing the correction. The important question of whether similar changes occur in humans has not been addressed. METHODS: We compared premonovision correction and the correction after at least 12 months of monovision soft contact lens wear (artificially induced anisometropia prescribed to focus one eye for near and the other for distance so that bifocal glasses are not needed) for 62 healthy predominantly female soft contact lens wearers and (a) 62 age- and sex-matched spectacle wearers and (b) 62 age- and generally sex-matched contact lens wearers. Control patients wore corrections of like power and had similar follow-up periods. RESULTS: Development of anisometropia occurred significantly more frequently among monovision wearers than among spectacle (p = 0.043) or contact lens wearing controls (p = 0.025). Changes in anisometropia greater than or equal to 0.50 D, with amounts up to 1.25 D, occurred in 29% of monovision wearers. CONCLUSIONS: Changes in refractive correction occur for adults who have monocular blur intentionally induced with monovision contact lenses. Similar changes may also occur after refractive surgery if one eye is corrected for a different distance than the other. Care should be taken when counseling presbyopic patients so that they are aware of the possibility of inducing refractive changes after monovision correction.     

Prospective clinical evaluation of the Acuvue Bifocal contact lens.

PURPOSE: We conducted a 15-month prospective clinical studyto evaluate the performance of the Acuvue Bifocal contact lens and to determine the objective and subjective factors that influence patient success rates in a general presbyopic population presenting to a contact lens specialist's office. METHODS: The first 100 patients who were initially fit and dispensed the Acuvue Bifocal contact lens are included in this study data. At each follow-up visit, visual acuity, slit lamp evaluation of lens/cornea relationship, and any change in ocular surface characteristics were noted. The study population was a general population with an interest in wearing disposable multifocal contact lenses. Success was defined as the patient actually purchasing the lens for continual wear. RESULTS: The overall success rate with the lens in this diverse study group was 53%. The majority of the successful patients achieved 20/25 or better distance and near acuity with the Acuvue Bifocal. None of the study participants had any adverse effect of lens wear or changes in keratometry or ocular surface characteristics. Of the successful patients, 57% wore the lens in a binocular fashion, while the remainder used some form of monovision. Virtually all patients rated lens comfort as excellent or very good, with the major factor in success or failure being visual performance. CONCLUSIONS: This prospective study in an average group of presbyopic contact lens or spectacle wearers yielded valuable insights into the performance of a disposable multifocal contact lens in a general contact lens practice. The Acuvue Bifocal should prove to be a valuable addition to the contact lens fitter's practice.     

Interest of presbyopes in contact lens correction and their success with monovision.

The presbyopic population is seen as a large potential source of contact lens wearers. The aims of this study were: (1) to estimate the percentage of presbyopes interested in contact lenses, (2) to ascertain the success of interested presbyopes with monovision correction, and (3) to determine the percentage willing to continue wearing monovision lenses after 1 month's trial. Seven practitioners in Sydney surveyed consecutive presbyopes attending their practices about their interest in contact lenses. Of the 1133 presbyopes surveyed, 314 (28%) were interested in trying monovision lenses. A total of 72 patients were subsequently fitted with monovision in high water content hydrogel form. After 1 month, 46 of these patients (64%) were still wearing the lenses, and 39 (54%) expressed willingness to continue with monovision correction. The major reasons for discontinuation from lens wear during the 1-month trial were inadequate vision and difficulty in lens handling.     

Rose-K contact lens for keratoconus

AIM: To report clinical experience and the comparative value of axial and instantaneous topography data in fitting Rose-K design contact lenses in moderate and severe keratoconus. MATERIALS AND METHODS: Thirty-eight eyes (of 23 patients) with keratoconus were fitted with Rose-K design contact lenses and followed up for at least six months or more. Visual acuity with habitual vision correction available was measured. Axial and instantaneous topography maps for each eye were recorded. Contact lens wear comfort was graded on a ten point rating scale every three months. RESULTS: Fourteen (100%) moderate keratoconus eyes (average Sim K 48.61 +/- 1.24D) and 23 of 24 (96%) of severe keratoconus eyes (average Sim K 60.88 +/- 5.31D) were successfully fitted with the Rose-K lenses. Final fit contact lenses in severe keratoconus had statistically significant steeper base curves compared to average axial corneal curvature than in moderate keratoconus eyes. Average simulated corneal curvature on axial maps predicted final fit contact lens base curves significantly better than on instantaneous maps. Thirty-three of the 37 eyes fitted with contact lenses maintained wear comfort over average follow up period of 13 +/- 3.5 months. CONCLUSIONS: Rose-K design rigid contact lenses are successful in visually rehabilitating 100% of moderate and 96% of severe keratoconus eyes. Most patients (90%) maintained contact lens wear comfort. Corneal curvature on axial maps is a better predictive of base curve of final fit contact lens.     

Short term responses to soft contact lens corrections for presbyopia

Eleven subjects were each fitted with five different soft contact lens corrections for presbyopia. The correction types were distance contact lenses with lookover spectacles, concentric bifocals, monovi-sion, modified monovision and progressive bifocal contact lenses. Subjects were asked to rate each contact lens correction in terms of distance, intermediate, near and peripheral vision, confidence when walking and climbing stairs, eye-hand co-ordination, performance on work tasks, vision difficulties in bright and dim ambient illumination and the correction most preferred for daily wear. There were few significant differences between ratings for the different corrections. Monovision, modified monovision and the concentric bifocal corrections were the preferred options for daily wear.     

An international survey of contact lens prescribing for presbyopia

Purpose: The aim was to determine world‐wide patterns of fitting contact lenses for the correction of presbyopia. Methods: Up to 1,000 survey forms were sent to contact lens fitters in each of 38 countries between January and March every year over five consecutive years (2005 to 2009). Practitioners were asked to record data relating to the first 10 contact lens fittings or refittings performed after receiving the survey form. Results: Data were received relating to 16,680 presbyopic (age 45 years or older) and 84,202 pre‐presbyopic (15 to 44 years) contact lens wearers. Females are over‐represented in presbyopic versus pre‐presbyopic groups, possibly reflecting a stronger desire for the cosmetic benefits of contact lenses among older women. The extent to which multifocal and monovision lenses are prescribed for presbyopes varies considerably among nations, ranging from 79 per cent of all soft lenses in Portugal to zero in Singapore. There appears to be significant under‐prescribing of contact lenses for the correction of presbyopia, although for those who do receive such corrections, three times more multifocal lenses are fitted compared with monovision fittings. Presbyopic corrections are most frequently prescribed for full‐time wear and monthly replacement. Conclusions: Despite apparent improvements in multifocal design and an increase in available multifocal options in recent years, practitioners are still under‐prescribing with respect to the provision of appropriate contact lenses for the correction of presbyopia. Training of contact lens practitioners in presbyopic contact lens fitting should be accelerated and clinical and laboratory research in this field should be intensified to enhance the prospects of meeting the needs of presbyopic contact lens wearers more fully.     

Ocular dominance testing

Clinicians typically apply the distance correction to the dominant sighting eye when fitting monovision contact lenses on presbyopic patients. This study investigates if this form of dominance testing correlates with a second type of dominance testing, the eye that will accept the least plus power when viewing a distance target binocularly. The plus lens test more closely simulates the condition under which the patient will be using the monovision correction. The theory is that the nondominant eye will accept more plus to blur than the dominant eye. Our study population consisted of subjects from the ages of 10 to 72 years. Fifty (64%) of the 78 subjects preferred the same eye by the plus lens testing as they did for sighting dominance. Seven subjects (9%) showed the opposite eye dominance with the plus lens test, and 21 subjects (27%) demonstrated no preference in the plus lens testing. The results could indicate that same-eye dominance on both tests may enhance the changes of a successful monovision adaptation.     

Comparison of multifocal and monovision soft contact lens corrections in patients with low-astigmatic presbyopia.

PURPOSE: The purpose of this study was to assess visual performance and patient satisfaction with two presbyopic soft contact lens modalities. METHODS: A crossover study of 38 patients with presbyopia was conducted. Patients were randomized first into either multifocal (Bausch & Lomb SofLens Multifocal) or monovision (SofLens 59) for 1 month. Visual performance was measured with high- and low-contrast visual acuity at distance and near and near stereoacuity. Patients' satisfaction was measured by the National Eye Institute Refractive Error Quality of Life Instrument questionnaire and by recording the patient's final lens preference. RESULTS: Patients maintained at least 20/20 binocular vision with both multifocal (MF) and monovision (MV) contact lenses under high-contrast conditions at distance and near. Under low-contrast conditions, patients lost less than a line of vision from the best spectacle correction to either multifocal or monovision contact lens correction at distance (pMF = 0.001, pMV = 0.006). Under low-contrast conditions at near, multifocal wearers lost five to six letters and monovision wearers lost two letters of vision (pMF < 0.001, pMV = 0.03, pMF/MV = 0.005). The average stereoacuity decreased by 79 s arc with monovision vs. multifocal contact lenses (p = 0.002). On the NEI-RQL, patients reported worse clarity of vision (pMF = 0.01, pMV < 0.001), more symptoms (pMF = 0.09, pMV = 0.01), and an improvement in their appearance with contact lens wear (pMF < 0.001, pMV < 0.001). Seventy-six percent of patients reported that they preferred multifocal contact lenses, and 24% preferred monovision contact lenses (p = 0.001). CONCLUSION: The majority of our patients preferred multifocals to monovision, most likely because the Bausch & Lomb SofLens Multifocal provides excellent visual acuity without compromising stereoacuity to the same degree as monovision.     

The effect of monovision contact lens wear on driving performance

Background : A number of studies have highlighted the problems with driving reported by wearers of monovision contact lens corrections. In this study, we wished to investigate this further, by determining whether driving performance as measured on the open road under daytime conditions is worse when drivers wear their monovision contact lenses compared to their habitual correction. Methods : Thirteen subjects with healthy eyes and corrected visual acuity of 6/6 were selected. Each had worn monovision contact lenses for at least three months. All subjects had their driving performance assessed while driving their own vehicles on an open road course, with both monovision contact lenses and their other habitual correction (spectacles or unaided). Results : No statistically significant differences were found in driving performance when subjects wore their monovision contact lenses compared to when they wore their habitual distance correction. Conclusions : The results indicate that monovision does not adversely affect driving performance in daylight hours for adapted wearers. However, limitations in the study design are acknowledged, including the relatively small sample size, lack of standardisation of the habitual correction and the use of adapted wearers. Future studies are recommended to investigate these issues further.     

Monovision contact lens wear and occupational task performance

The effects of monovision (MV) contact lens wear on the performance of occupational-type nearpoint tasks was evaluated on 18 presbyopic subjects (ages 44 to 67 years) by comparing MV performance (MV condition) to that with distance contact lenses with reading glasses (BV condition). Each subject had correctable distance visual acuity of 6/6 (20/20) in each eye, at least 60 sec arc of near stereopsis, good ocular health, and no previous MV experience. Time performance and error performance for 3 nearpoint occupational tasks (pointers and straws, card filing, and letter editing) were measured with the MV correction and BV correction. Measurements were taken at dispensing and at 2 weeks and 8 weeks after dispensing. Subjects were instructed to wear the MV soft spherical contact lenses at least 8 h per day. We measured BV time performance to be better than MV time performance by 2.8 to 5.7% and also measured an increased number of errors with MV.     

Sighting dominance and monovision distance binocular fusional ranges.

Clinicians typically apply the distance correction to the dominant sighting eye in fitting presbyopic patients with monovision (MV) contact lenses. We evaluated the effect of this fitting strategy on distance binocular fusional ranges for 23 presbyopic subjects. This sample was composed of successful and unsuccessful MV wearers. Fusional ranges for the two MV fitting possibilities (distance lens on the dominant eye, near lens on the dominant eye) were compared to fusional ranges in which both eyes were fitted with the distance correction. A greater esophoric shift and greater reduction in vergence ranges were demonstrated when the non-dominant eye received the clear image compared to when the dominant eye received the clear image. Successful MV patients demonstrated these effects to a lesser degree than did unsuccessful patients. In general, effects of MV on distance binocular fusional ranges were fewer when successful MV subjects received the clear image in the dominant eye.     

Surgical monovision and monovision reversal in LASIK

PURPOSE: This study was designed to assess the success of surgical monovision in presbyopic patients. METHODS: A university refractive surgery center retrospective chart review of 82 patients who elected to undergo surgical monovision with laser in situ keratomileusis (LASIK) between January 2000 and January 2003 was conducted. Specific factors included for analysis included preoperative and postoperative defocus spherical equivalent, whether the patient underwent enhancements, whether the patient underwent a preoperative monovision trial with contact lens, and whether the patient underwent monovision reversal. RESULTS: Eighty-two patients who underwent LASIK for monovision were analyzed. Mean preoperative spherical equivalent in the distance-corrected eye was -4.07 (standard deviation (SD), 2.49); for the eye corrected for near vision, mean preoperative spherical equivalent was -4.10 (SD, 2.56). Postoperative spherical equivalent in the distance eyes was -0.01 (SD, 0.38) and in the near eyes -1.24 (SD, 0.91). There were 6 enhancements in the near eyes (7%) and 17 enhancements in the distance vision eyes (21%). This difference was statistically significant (P = 0.007). Thirty patients underwent a contact lens trial of monovision before LASIK, and none of those patients elected monovision reversal. There were 52 patients who did not undergo a contact lens monovision trial before LASIK monovision, and 2 of these patients underwent monovision reversal. Monovision success in this population was 97.6%. CONCLUSION: Surgical monovision can help presbyopic patients achieve their goal of reduced dependence on spectacles. A trial of monovision contact lenses or spectacles may be important in helping surgeons select patients for successful surgical monovision.     

Current Australian attitudes to contact lens extended wear

A survey form was distributed to 262 members of the Contact Lens Society of Australia, and 109 replies were received. The results indicate that the majority of contact lenses prescribed for extended wear were because of patient request or patient convenience. Most practitioners were selective with the types of patients fitted with lenses for extended wear, with 84% fitting this lens form. Those who did not prescribe this lens form were not prepared to tolerate the perceived associated risks of extended wear. Ninety-two percent of contact lenses prescribed for extended wear were hydrogels, with frequent lens removal and replacement recommended. Sixteen percent of respondents had seen patients with complications as a result of contact lens extended wear. Disadvantages of extended wear are discussed. Contact lens extended wear is apparently losing popularity amongst practitioners.     

Contact lens fitting following corneal graft surgery

Contact lens fitting may be required following keratoplasty for either optical or thera‐peutic reasons. Optical indications for contact lens fitting include the correction of irregular astigmatism, high regular astigmatism, anisometropia and secondary aniseikonia, as well as simple ametropia, where the patient desires to wear contact lenses in preference to spectacles. Therapeutic lenses are not routinely fitted following kerate plasty, although this management is advised in certain cases, such as when there are protruding sutures or epithelial healing is impaired. Designing a contact lens for a patient who has undergone keratoplasty will require the practitioner to carefully assess all the relevant features of the corneal graft. In this regard, there are many factors that need to be considered including the diameter of the graft zone, the topographical relationship between the host cornea and donor cornea, the corneal (graft) toricity and the location of the graft. Special designs, such as reverse geometry lenses, or more complex contact lens modalities, such as piggyback contact lens systems, may be required to achieve success in fitting.     

Monovision pseudophakia

PURPOSE: To evaluate distance and near binocular visual acuities and patient acceptability after sequential posterior chamber intraocular lens (PC IOL) implantation for pseudophakic monovision correction. SETTING: Private practice and the Manhattan Eye Ear and Throat Hospital, New York, New York, USA. METHODS: This study comprised 140 binocular patients with less than 2.00 diopters (D) of astigmatism. Preoperatively, all patients expressed a desire to be independent of optical correction; 120 presented for removal of visually significant cataract and 20, for correction of high ametropia (+8.00 to -14.00 D). Phacoemulsification and implantation of a PC IOL calculated to achieve emmetropia were performed in the dominant eye. Ocular dominance was confirmed on multiple preoperative visits using a sighting technique. Implantation of a PC IOL calculated to yield a spherical equivalent of -2.75 D was performed in the nondominant eye. Seven postoperative examinations were performed during the 1-year follow-up, with 96 patients completing all evaluations. At each examination, interviews were conducted on patient acceptance and ability to perform near and distance tasks without correction. RESULTS: In the entire study group, 129 patients (92%) achieved 20/30 or better uncorrected distance acuity, J1 or better uncorrected near acuity, or both. One hundred ten patients (91%) in the cataract group and 19 (95%) in the clear lens group achieved this level. Patient acceptance was 90% in the cataract group and 100% in the clear lens group. CONCLUSIONS: In a diverse group of self-selected patients from 1 metropolitan-area ophthalmology practice who were motivated to be free of spectacles, pseudophakic monovision provided a high level of satisfaction. No morbidity was associated with monovision as those who were dissatisfied with their uncorrected state did well with spectacle or contact lens correction.     

Presbyopic fitting strategies: Fitting lenses to patients,not patients to lenses

Eighty-six presbyopic patients who were interested in contact lens wear but had no history of using contact lenses for the correction of presbyopia were entered into a study performed across five independent contact lens practices. Patients were fit utilizing a fitting strategy flowchart that included monovision, diffractive, and aspheric simultaneous and alternating vision presbyopic corrections. At the conclusion of the study, 83% of the patients were successful utilizing the criterion that the patient was still actively wearing the lenses. Fifty-two percent were fit with monovision, 14% were fit in alternating vision lenses, while 6% and 10% were fit with aspheric and diffractive lenses, respectively, including modified monovision.     

Ocular dominance and patient satisfaction after monovision induced by intraocular lens implantation

PURPOSE: To elucidate the relationship between ocular dominance and patient satisfaction with monovision induced by intraocular lens implantation. SETTING: Eye Clinic, Kitasato University School of Medicine Hospital, Sagamihara, Kanagawa, Japan. METHODS: The durations of exclusive visibility of dominant- and nondominant-eye targets were measured in 16 patients with successful monovision and 4 patients with unsuccessful monovision to determine the characteristics of ocular dominance. The dominant eye was determined using the hole-in-card test (sighting dominance). The contrast of target in nondominant eye was fixed at 100%; the contrast of target in the dominant eye varied (ie, 100% to 80% to 60% to 40% to 20%) using rectangular gratings of 2 cycles per degree that were 4 degrees in size. RESULTS: In the successful monovision group, the reversal thresholds (ie, exclusive visibility of the nondominant eye crosses over that of the dominant eye) were displayed only at low decreasing contrast (80% and 60%). However, in the unsuccessful monovision group, the reversal thresholds were at high decreasing contrast (20%) or not at all. The reversal thresholds in patients with unsuccessful monovision were at a significantly lower contrast than in patients with successful monovision (P<.05). CONCLUSIONS: Success and patient satisfaction in monovision patients were significantly influenced by the magnitude of ocular dominance. The balance technique seems to be a good method to evaluate the quantity of ocular dominance and prospectively evaluate the monovision technique.     

The holographic/diffractive bifocal contact lens

Presently, practitioners are somewhat limited in the available options for correction of presbyopia with contact lenses. Neither the form of contact lens design (segmented, aspheric, or concentric) or fitting scheme (such as monovision) have high enough success to dominate the market. To meet this growing demand, a new holographic/diffractive bifocal contact lens is being introduced by several manufacturers^1,2,3,4,5. Although different lens materials and slightly modified designs have been proposed, these lenses all form images based upon a similar concept. This paper attempts to simplify the principles behind “how the holographic bifocal contact lens works.” This will include a review of diffraction and refraction as well as the application of these concepts in the diffractive lens design. Comparisons between the holographic and conventional bifocal contact lenses along with advantages and disadvantages will also be presented.     

Comparative visual performance of three presbyopic contact lens corrections.

We compared the visual performance of a soft diffractive (DIFF) bifocal contact lens, a near center (CN) concentric bifocal design, and monovision (MV), using a comprehensive vision testing protocol. Fifteen presbyopic subjects who were successfully wearing DIFF bifocal contact lenses participated in the study. Of the three systems tested, MV provided best visual acuity at distance and near; less than one line of acuity was lost relative to best spectacle acuity under all lighting and contrast conditions, and there was less disturbance of a point source of light. Both bifocal corrections gave similar visual acuity performance, with more lines of acuity lost relative to spectacles at near compared to distance. However, the concentric bifocal induced more ghosting at near than the other two systems. Stereopsis was compromised at distance with MV correction, but all systems performed worse than spectacles at near. An understanding of the strengths and weaknesses of presbyopic contact lens options allows the clinician to improve management of the presbyope who wishes to wear contact lenses.