Impact of monovision on dynamic accommodation of early presbyopes

Abstract

Purpose To examine the impact of monovision on dynamic changes in accommodation, pupil responses, spherical aberration and resultant image quality in early presbyopes. Methods Refractive state, pupil size and spherical aberration levels were monitored in nine early presbyopes who exhibited some accommodation (40–50 years, mean = 42 ± 2.37 years) using a Shack‐Hartmann aberrometer as a binocularly viewed stimulus stepped closer (from 2 m to 40 cm), or farther (from 40 cm to 2 m). Comparison data from two fully presbyopic (i.e. non‐accommodating) subjects (ages 46 and 61 years) and two young adults (ages 26 and 29 years) were also collected. Each subject was fit with four different refractive strategies: (1) both eyes corrected for 2 m, (2) both eyes corrected for 40 cm, (3) monovision with the measured right eye corrected for 2 m and, (4) monovision with the right eye corrected for 40 cm. Monochromatic image quality was quantified using the AreaMTF metric. Results When fit with monovision, the largest number of early presbyopes produce an accommodative response dominated by the right eye correction (distance or near) as the stimulus is abruptly changed from the retinal conjugate plane of one eye to that of the other eye. However, the accommodative responses in some early presbyopes were always dominated by the distance corrected eye, the near corrected eye, or by convergence. When the stimulus approached, the near corrected eye experienced high image quality only if there was no accommodative response. However, reduced image quality was observed if an accommodative response was initiated. Neither accommodation nor pupil response latencies were longer with monovision corrections compared with bilateral distance corrections (p > 0.05). In the early presbyopes, spherical aberration was reduced during near viewing, but primarily due to pupil miosis and not lens shape changes. Conclusion As the stimulus was abruptly changed from the retinal conjugate plane of the distance corrected eye to that of the near corrected eye, most early presbyopes fit with monovision accommodated, which resulted in a decline, not an increase in image quality in the near corrected eye. These results reveal a non‐optimal accommodative strategy in early presbyopes fit with monovision.

Refractive outcomes and optical quality of PRESBYOND laser-blended vision for presbyopia correction

“…Hayashi et al [26] also found that modified monovision (0.75 D anisometropia) yielded worse near vision than traditional monovision (1.75 D anisometropia). Another possible mechanism proposed by Almutairi et al [30] was that the accommodative response reduced the image quality when the stimulus approached. Presbyopia correction cannot easily yield the best of both far and near vision.…”

Effectiveness of SMILE Combined with Micro-Monovision in Presbyopic Patients: A Pilot Study

“…Although micro-monovision studies have been conducted with older LRS techniques such as LASIK or photorefractive keratectomy (PRK) [ 2 ], few studies have been conducted with the combination of SMILE and micro-monovision, mainly because it is a more recent technique [ 6 , 7 , 8 ]. In addition, although the usual clinical practice procedure involves the correction of distance vision in the dominant eye and near vision in the non-dominant eye [ 6 , 7 , 8 ], recent laboratory research suggests that the vision of a patient undergoing a monovision procedure may vary according to different patterns of accommodative response [ 9 ], as presbyopic patients in their 40s and 50s still retain some accommodative capabilities. Thus, depending on the accommodative response, the patient may achieve a different range of clear vision.…”