6 Special Situations Abstract Keywords: monovision to correct diplopia, gender and IOL monovision, age and IOL monovision, pupil size and IOL monovision, sidedness of ocular dominance, peripheral field and monovision, over-the-counter readers and IOL monovision Some studies have shown a unique function of monovision as a means to correct symptomatic diplopia.1,2,3,4 The principle of this approach is based on further suppression from monovision-induced anisometropia to dampen diplopia awareness. For nondiplopic presbyopic patients, we use monovision to increase depth of focus by binocular summation and monocular blur suppression. Therefore, we try to avoid those who have any history of strabismus, diplopia, or prism correction because we do not want to interrupt and compromise the existing balanced binocular function if they are currently not diplopic. However, for those patients who are already diplopic with stable strabismus, which is the main clinical problem for these patients, we can use monovision to further disassociate the two eyes, while retaining a good field of vision, monocular acuity, and gross peripheral stereopsis. Bujak et al1 did a prospective study with 20 presbyopic patients (older than 45 years) who had symptomatic diplopia due to secondary strabismus with a deviation angle of 10 prism diopters or less and were stable for at least 3 months. Mean duration of diplopia was 44.3 months, ranging from 6 to 96 months. Subjects were excluded if they were not presbyopic or if they were satisfied with their previous prism correction for their diplopia. Each received monovision spectacles, contact lenses, or both, with distance correction in the dominant eye, as determined by the hole-in-card test. Half received a + 3.00-diopter add and the other half received + 2.50 diopters. Based on the results of the Diplopia Questionnaire, 85% of patients experienced significant improvement in diplopia symptoms after monovision correction. The quality of life score also increased significantly. There was improved social contact and appearance (p = 0.0002) with increased self-confidence resulting from personal appearance. There was no significant difference between the 2.50 D group and 3.00 D group. In spite of the advantages and benefits of purposeful monovision with either glasses or contact lenses, or both, the study did demonstrate some associated problems from this approach, such as difficulty in estimating distance, checking driving blind spots, and climbing or descending stairs. Another study reported seven cases of diplopic patients successfully treated with contact lens monovision.2 The author made the recommendation to instruct the patient not to think about which eye was seeing at which distance. Instead, encourage the patient to view the target of regard clearly. Prescribing distance correction for the less mobile eye also helped overall performance. Extreme intraocular lens (IOL) monovision with 3.00 D or more anisometropia (9 out of 12 had 3.00 diopters or more and the remaining 3 had 2.00 to 3.00 diopters) was reported by Osher et al4 to be successful in managing longstanding stable secondary diplopia in 12 patients. Those patients demonstrated the elimination or significantly decreased awareness of preoperative diplopia and achieved significant spectacle independence and high postoperative satisfaction. All the patients were warned of a possibility of surgical reversal if that new extreme IOL monovision should fail for any reason. All 12 cases attained excellent uncorrected distance vision and uncorrected near vision. There were no surgical reversals or postoperative prisms needed for any patient. No patient reported being dissatisfied. This is certainly an interesting and novel approach for longstanding stable secondary diplopia in patients with bilateral visually significant cataracts. A number of laser vision correction studies demonstrate that slightly more women chose monovision than men.5,6,7,8 The cosmetic aspects could be one motivation. No data are known demonstrating whether one gender has greater success with monovision.
Monovision correction shows promise as an alternative treatment for patients with longstanding symptomatic but stable secondary diplopia. This may be accomplished with contact lenses or intraocular lenses (IOLs), if conventional management fails to promote fusion function. This approach should be considered with caution. More female than male patients choose laser vision correction monovision. Age does not seem to have a major impact on IOL monovision. Patients with a successful history of contact lens or laser vision correction monovision are almost universally good candidates for IOL monovision and the same pattern should be kept regardless of the dominant eye test. Patients with large pupils are probably less favorable for IOL monovision for nighttime driving. Pseudophakic monovision does not seem to have a negative impact on peripheral vision. Just like hand and foot sidedness, more people have their right eye as their sighting dominant eye than their left eye. Pseudophakic monovision may have a short period of adaptation, but no known study exists on this subject. When needed, non-customized over-the-counter readers seem to work quite well for most mini and modest level anisometropic IOL monovision patients.
6.1 Monovision to Correct Diplopia
6.2 Other Factors Affecting Monovision
6.2.1 Gender
6.2.2 Age
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