The effect of different monovision contact lens powers on the visual function of emmetropic presbyopic patients (an American Ophthalmological Society thesis)

Abstract

Purpose: To evaluate the effects of three increasing powers of monovision contact lenses on both objective and subjective vision in emmetropic presbyopic patients.

Methods: A prospective single-center study was conducted on 50 emmetropic presbyopic patients with a mean age of 55.4 +/- 4.3 years (range, 50 to 66). Each patient wore for 1 week a +0.75 D, +1.50 D, and +2.50 D contact lens in the nondominant eye. Objective testing after each week included near and distance visual acuity, distance stereopsis, distance contrast sensitivity, and measurement with two different aberrometers of spherical equivalent, defocus, spherical aberration, and total higher-order aberrations. Subjective testing included questionnaire responses regarding vision under various conditions after 1 week with each lens power. Statistical tests were performed to determine significant differences from pretreatment.

Results: Binocularly, mean uncorrected near visual acuity increased in both eyes (P < .01) with each increase in contact lens power. Monocular distance vision decreased significantly with each increasing lens power, but binocular distance vision remained unchanged from pretreatment. Distance stereopsis decreased significantly with increasing contact lens powers (P < .01 with the +2.50 D lens power). Photopic and mesopic distance contrast sensitivity decreased significantly with progressive increase in power. Wavefront analysis showed a change in defocus in the myopic direction, but no increase in higher-order aberrations.

Conclusions: In emmetropic presbyopes, near vision improved with increased lens power, but distance vision was degraded objectively and subjectively. The +1.50 D power provided optimal near and distance vision for monovision contact lens wear, as measured by a patient questionnaire and a series of eight tests for evaluating various aspects of visual function. The objective and subjective tests used in this study will provide a baseline for evaluation of surgical procedures performed for near vision enhancement.

FIGURE 1

Available diopters of accommodation with age. Diminishing accommodation with age is evident. At age 50, accommodation is less than 3 diopters. Data from Duane and Donders.

FIGURE 2

Refractive error distribution in adults 40 years of age or older. Emmetropic and +1.0 D persons constitute 41% of the population of 40 or older persons. Data from Tielsch et al.

FIGURE 3

Testing for eye dominance. The card is held at arm’s length with patient sighting at a distant target over card with both eyes.

FIGURE 4

Testing for eye dominance. A distant object is sighted over the card.

FIGURE 5

Testing for eye dominance. The distant object is sighted through hole in the card.

FIGURE 6

Testing for eye dominance. When the card reaches the face, the dominant eye is obvious to both the doctor and patient.

FIGURE 7

Mean logMAR uncorrected distance visual acuity for treated and untreated eyes at pretreatment and with the +0.75 D, +1.50 D, and +2.50 D contact lenses. CL = contact lens (N = 50 for pretreatment, +0.75 D, and +1.50 D lenses; N = 49 for +2.50 D lens).

FIGURE 8

Quality of vision pretreatment and with three powers of contact lenses. Subjective response to question, “My distance vision pretreatment and with my present correction is excellent.” Statistically significant changes from pretreatment shown with asterisk. CL = contact lens (N = 50 for pretreatment, +0.75 D, and +1.50 D lenses; N = 49 for +2.50 D lens).

FIGURE 9

Subjective response to question, “Are you having problems with the clarity of your vision?” CL = contact lens (N = 50 for pretreatment, +0.75 D, and +1.50 D lenses; N = 49 for +2.50 D lens).

FIGURE 10

Subjective response to question, “Are you having problems with halos, rings, or starbursts?” CL = contact lens (N = 50 for pretreatment, +0.75 D, and +1.50 D lenses; N =49 for +2.50 D lens).

FIGURE 11

Subjective response to question, “Are you having problems with glare affecting your vision?” CL = contact lens (N = 50 for pretreatment, +0.75 D, and +1.50 D lenses; N = 49 for +2.50 D lens).

FIGURE 12

Subjective response to question, “Are you having problems with haze affecting your vision?” CL = contact lens (N = 50 for pretreatment, +0.75 D, and +1.50 D lenses; N = 49 for +2.50 D lens).

FIGURE 13

Mean uncorrected near visual acuity (logMAR) for treated and untreated eyes at pretreatment and with the +0.75 D, +1.50 D, and +2.50 D contact lenses. Statistically significant changes from pretreatment shown with asterisk. CL = contact lens (N = 50 for pretreatment, +0.75 D, and +1.50 D lenses; N = 49 for +2.50 D lens).

FIGURE 14

Subjective response to question, “Using both eyes, my near vision pretreatment and with the current contact lens is excellent?” Statistically significant changes from pretreatment shown with asterisk. CL = contact lens (N = 50 for pretreatment, +0.75 D, and +1.50 D lenses; N = 49 for +2.50 D lens).

FIGURE 15

Percent of daily tasks completed without near add spectacles. Statistically significant changes from pretreatment shown with asterisk. CL = contact lens (N = 50 for pretreatment, +0.75 D, and +1.50 D lenses; N = 49 for +2.50 D lens).

FIGURE 16

Mean distance stereopsis (seconds of arc) with the change in monovision power. Statistically significant changes from pretreatment shown with asterisk. CL = contact lens (N = 50 for pretreatment, +0.75 D, and +1.50 D lenses; N = 49 for +2.50 D lens).

FIGURE 17

Mean log photopic contrast sensitivity (CS): treated eye. Pretreatment and with increasing power of monovision contact lenses. Statistically significant changes from pretreatment shown with asterisk. CL = contact lens; cpd = cycles per degree. (N = 50 for pretreatment, +0.75 D, and +1.50 D lenses; N = 49 for +2.50 D lens)

FIGURE 18

Photopic contrast sensitivity: percent change from pretreatment: treated eyes. Statistically significant changes from pretreatment shown with asterisk. CL = contact lens; cpd = cycles per degree. (N = 50 for +0.75 D and +1.50 D lenses; N = 49 for +2.50 D lens)

FIGURE 19

Mean log mesopic contrast sensitivity (CS): treatment eye. Pretreatment and with increasing power of monovision contact lenses. Statistically significant changes from pretreatment shown with asterisk. CL = contact lens; cpd = cycles per degree. (N = 50 for pretreatment, +0.75 D, and +1.50 D lenses; N = 49 for +2.50 D lens)

FIGURE 20

Mesopic contrast sensitivity: percent change from pretreatment: Treated eyes. Statistically significant changes from pretreatment shown with asterisk. CL = contact lens; cpd = cycles per degree. (N = 50 for +0.75 D and +1.50 D lenses; N = 49 for +2.50 D lens)

FIGURE 21

Mean log photopic contrast sensitivity (CS): both eyes. Pretreatment and with increasing power of monovision contact lenses. Statistically significant changes from pretreatment shown with asterisk. CL = contact lens; cpd = cycles per degree. (N = 50 for pretreatment, +0.75 D, and +1.50 D lenses; N = 49 for +2.50 D lens)

FIGURE 22

Photopic contrast sensitivity: percent change from pretreatment: Both eyes. CL = contact lens; cpd = cycles per degree. (N = 50 for +0.75 D and +1.50 D lenses; N = 49 for +2.50 D lens). No decreases from pretreatment are statistically significant.

FIGURE 23

Mean log mesopic contrast sensitivity (CS): both eyes. Pretreatment and with increasing power of monovision contact lenses. CL = contact lens; cpd = cycles per degree. (N = 50 for pretreatment, +0.75 D, and +1.50 D lenses; N = 49 for +2.50 D lens)

FIGURE 24

Mesopic contrast sensitivity: percent change from pretreatment: treated eyes. Statistically significant change from pretreatment shown with asterisk. CL = contact lens; cpd = cycles per degree. (N = 50 for +0.75 D and +1.50 D lenses; N = 49 for +2.50 D lens)

FIGURE 25

Subjective responses. The effect of increasing monovision on the patients’ ability to read newspaper headlines. Statistically significant change from pretreatment shown with asterisk. CL = contact lens. (N=50 for +0.75 D and +1.50 D lenses; N=49 for +2.50 D lens)

FIGURE 26

Subjective responses. The effect of increasing monovision on the patients’ ability to see automobile dashboard. Statistically significant change from pretreatment shown with asterisk. CL = contact lens. (N = 50 for +0.75 D and +1.50 D lenses; N = 49 for +2.50 D lens)

FIGURE 27

Subjective responses. The effect of increasing monovision on the patients’ ability to see computer screen. CL = contact lens. Statistically significant changes shown from pretreatment with asterisk. N = 50 for +0.75 D and +1.50 D lenses; N = 49 for +2.50 D lens)

FIGURE 28

Subjective responses. The effect of increasing monovision on the patients’ ability to see their watch. Statistically significant changes from pretreatment shown with asterisk. CL = contact lens. (N = 50 for +0.75 D and +1.50 D lenses; N = 49 for +2.50 D lens)

FIGURE 29

Subjective responses. The effect of increasing monovision on the patients’ ability to see their cellular phone. Statistically significant changes from pretreatment shown with asterisk. CL = contact lens. (N = 50 for +0.75 D and +1.50 D lenses; N = 49 for +2.50 D lens).

FIGURE 30

Subjective responses. The effect of increasing monovision on the patients’ ability to see a medicine bottle label. Statistically significant changes from pretreatment shown with asterisk. CL = contact lens. (N = 50 for +0.75 D and +1.50 D lenses; N = 49 for +2.50 D lens)

FIGURE 31

Subjective responses. “My ability to judge distances is excellent.” Statistically significant changes from pretreatment shown with asterisk. CL = contact lens. (N = 50 for +0.75 D and +1.50 D lenses; N = 49 for +2.50 D lens)

FIGURE 32

Total higher-order aberrations error (μm) for patients wearing three different powers of contact lenses; measured with the Alcon LadarWave aberrometer, 6.0-mm pupil; the Tracey Visual Function Analyzer, 6.0-mm pupil; and the Tracey Visual Function Analyzer, 3.0-mm pupil. (N = 50 for +0.75 D and +1.50 D lenses; N = 49 for +2.50 D lens). Statistically significant differences for actual minus expected shown with asterisk.