A 62-year-old female university professor presented with complaints of dryness and near blur with wear of her monthly replacement spherical soft contact lenses. She reported that her lenses were “corrected for monovision.”
Her distance acuity was 20/20 in the right eye and 20/30 in the left eye. Her near acuity was 20/60 in the right eye and 20/40 in the left eye. Further testing showed that her left eye power was biased for near by 0.75D. Slit lamp examination revealed lenses that were centered and moving well on the ocular surface. There were no apparent signs of dry eye in either eye.
Studies have reported the comfort of daily disposable lenses to be superior to other lens modalities in which lenses are exposed to either multipurpose or hydrogen peroxide systems (Lazon de la Jara et al, 2013). Some evidence suggests that both care systems can lead to increased surface roughness (Lira et al, 2014). As one of the patient’s chief complaints was discomfort, it was recommended that she be refit into daily disposable soft lenses.
Pros and Cons
But, what are the options to improve her near vision?
Increasing Monovision Providing additional plus in her nondominant left lens is simple and will likely improve her near vision. However, it may also create problems at the intermediate distance, which is important because she spends multiple hours on the computer each day. Increasing the disparity between the eyes may also lead to problems with depth perception and distance blur, particularly with activities such as night driving (Table 1).
Multifocal Approach Multifocal lenses are more costly compared to single-vision lenses and may require more time to arrive at the best prescription. However, patients experience better binocularity and visual performance during real-life activities with multifocals compared to those wearing monovision correction (Woods et al, 2009). Therefore, daily disposable multifocal correction would be ideal.
The Multifocal Fitting
Center-near aspheric daily disposable multifocals were fit according to the manufacturer’s fitting guide, employing a high add in each eye. The patient reported good initial comfort and vision. Binocular acuity was 20/20 at distance and 20/25 at near. Lenses were dispensed, and she was asked to return in approximately one week.
Nine days later, she returned reporting excellent comfort but difficulty with near tasks. Binocular acuity was 20/20 at distance and 20/60 at near. A loose lens over-refraction indicated no change in distance power. Because the patient was already in a high add, additional plus was demonstrated over the nondominant left eye. She reported vastly improved near vision with +0.50D over the left eye without any appreciable binocular reduction in distance vision. The new power was dispensed. During a telephone follow up six days later, the patient reported good vision at all distances. The prescription was finalized and an annual supply ordered for delivery to her home.
While this patient did quite well, some who are longtime monovision wearers sometimes have difficulty adapting to the simultaneous vision optics of multifocal lenses. In these cases, simply refit the near-biased eye with a multifocal, keeping the distance-biased eye in a single-vision lens. This approach often keeps patients happy with their distance vision while eliminating the problems of distance glare and intermediate blur induced by a highly over-plussed single-vision lens on the monovision near eye. CLS