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Results for “PRESBYOPIA”

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At least 145 records · Page 8Linked to original sources
PubMed1989

Accommodation and presbyopia in the human eye--aging of the anterior segment.

Ocular biometric parameters and accommodative amplitude were measured by various techniques in 100 normal emmetropic human subjects age 18-70 yr. Anterior chamber depth decreased and lens thickness increased linearly over the entire age group. Accommodative amplitude declined linearly until a stable nadir was reached at about age 50 yr. The respective slopes and intercepts of the age-dependent decline in anterior chamber depth were essentially the same for measurements made independently by optical pachmetry, A-scan ultrasonography, and slit-lamp Scheimpflug photography. The age-dependent increase in lens thickness differed in slope and intercept for measurements made by photography and ultrasonography if the generally accepted lenticular sound velocity was assumed for all subjects. However, if putative lenticular sound velocity was adjusted for age, the relationships given by the two techniques were essentially identical. Total anterior segment length (defined as the distance between the anterior corneal and posterior lens surfaces), vitreous cavity length (distance between the posterior lens and anterior retinal surfaces), and total globe length were all independent of age. This constellation of findings indicates that the human lens grows throughout adult life while the globe does not, that thickening of the lens completely accounts for shallowing of the anterior chamber with age, but that the posterior surface of the lens remains fixed in position relative to the cornea and retina.

Accommodation, Ocular↗
PubMed2004

Effectiveness of multifocal intraocular lenses to correct presbyopia after cataract surgery: a randomized controlled trial.

PURPOSE: Although monofocal intraocular lenses (IOLs) are effective in improving vision after cataract surgery, the loss of accommodation is not restored by implantation of these IOLs. Because multifocal IOLs may improve uncorrected distance and near vision, we compared the clinical outcome and patient satisfaction after implantation of monofocal and multifocal IOLs. Sociodemographics, eagerness for spectacle independence (ESI), and neuroticism were tested as predictors of satisfaction. DESIGN: Randomized controlled trial. PARTICIPANTS: Cataract patients with no ocular comorbidity were operated from August 1999 to January 2001; 75 patients were implanted with monofocal IOLs, and 78 with multifocal IOLs. METHODS: Assessments were made preoperatively (t1), 3 months after first-eye surgery (t2), and 3 months after second-eye surgery (t3). Primary outcomes were obtained by ophthalmic tests, whereas secondary outcomes were examined by interviews. MAIN OUTCOME MEASURES: Primary outcomes consisted of near and distance visual acuity (VA). Secondary outcomes related to spectacle dependence, vision-related functioning, and patient satisfaction. RESULTS: At t3, multifocal IOLs showed significantly better uncorrected near VA than monofocal IOLs (P<0.01) and an increase in quality ratings of unaided near vision between t1 and t3 (on a scale of 1-5: 1.6 at t1 vs. 2.9 at t3, P<0.001). At t2 and t3, patients with multifocal IOLs were more likely to "never" or "only now and then" wear spectacles for near and distance than patients with monofocal IOLs (at t3, 42.7% multifocal vs. 21.6% monofocal for near [P = 0.002] and 75.0% multifocal vs. 46.2% monofocal for distance [P = 0.001]). On a 0- to 15-point scale, monofocal IOL patients showed fewer complaints from cataract symptoms, including halos and distorted vision, at t3 (1.2 monofocal vs. 2.1 multifocal [P = 0.002]). Satisfaction related to preoperative expectations was similar in the monofocal and multifocal groups. The perceived quality of corrected near vision had the strongest relationship with patient satisfaction (beta = 0.22; 95% confidence interval: 0.060-0.523). Sociodemographics, ESI, and neuroticism did not predict patient satisfaction. CONCLUSIONS: Overall, patient satisfaction did not differ between the groups of monofocal and multifocal IOLs. Independent of ESI or neuroticism scores, success of both IOLs depends on preoperative expectations and postoperative quality of aided near vision. This article contains additional online-only material available at .

Accommodation, Ocular↗
PubMed2006

Evidence for delayed presbyopia after photorefractive keratectomy for myopia.

PURPOSE: To evaluate uncorrected near visual acuity (NVA), accommodation, corneal aberrations, and the optical quality of the retinal image in presbyopic eyes after photorefractive keratectomy (PRK). DESIGN: Nonrandomized comparative retrospective study. PARTICIPANTS: Ten post-PRK patients and 10 normal patients. METHODS: Twenty eyes (10 right and 10 left after PRK for myopia, minimum of 10 years after the operation; group A) were compared with 20 eyes (10 right and 10 left age- and gender-matched normal controls; group B). All subjects were over 40 years of age. MAIN OUTCOME MEASURES: With best distance correction, NVA was measured at 40 cm (Jaeger, J series), and the range of accommodation (diopters [D]) was measured subjectively (negative relative amplitude and positive relative amplitude). The modulation transfer function (MTF) and corneal aberrations such as comalike, spherical (SAs), and higher order (HOAs) were measured with a Hartmann-Shack aberrometer. From the MTF curves, the spatial frequencies corresponding to contrast values of 0.1 and 0.5 were noted. RESULTS: Mean ages (+/- standard deviations [SDs]) were 46.3 years (4.7) for group A and 47.6 years (4.9) for group B (P>0.05). Near acuity was J1 or better in 12 of 20 post-PRK and 4 of 20 control eyes. Mean accommodations (+/- SDs) were 3.2 D (1.14) for right group A eyes and 2.1 D (0.94) for right group B eyes (P = 0.0152), and 3.4 D (0.99) for left A eyes and 2.3 D (1.02) for left B eyes (P = 0.0168). Total HOA indexes (+/- SDs) were 1.449 (0.409) for right group A eyes and 0.824 (0.241) for right group B eyes (P = 0.008), and 1.464 (0.388) for left A eyes and 1.067 (0.542) for left B eyes (P = 0.0752). Pooling the data from post-PRK and control eyes, a significant correlation was found between near acuity and SA (right eyes, r = -0.535, P = 0.015; left eyes, r = -0.493, P = 0.027). Significant associations were found between accommodation, near acuity, HOA, and comalike aberration for right eyes only. Mean spatial frequencies (+/- SDs) corresponding to contrast values of 0.1 for right and left eyes were 14.96 (5.71) for right group A eyes and 22.02 (6.85) for right group B eyes (P = 0.074), and 15.11 (7.80) for left A eyes and 21.41 (9.00) for left B eyes (P = 0.271). Mean spatial frequencies (+/- SDs) corresponding to contrast values of 0.5 for right and left eyes were 2.86 (0.63) for right group A eyes and 3.21 (0.35) for right group B eyes (P = 0.596), and 2.76 (0.98) for left A eyes and 3.22 (0.27) for left B eyes (P = 0.194). CONCLUSIONS: Compared with normal eyes, in previously myopic eyes treated with first-generation PRK lasers there is a tendency for (1) the optical quality of the retinal image to be reduced at low contrast, (2) the aberrations attributed to the corneal surface to increase, and (3) both measured subjective accommodation and near acuity to be greater than expected. We postulate that the corneal aberrations induced by PRK for myopia may reduce the quality of the retinal image for distance but enhance near acuity by way of a multifocal effect that can delay the onset of age-related near vision symptoms.

Accommodation, Ocular↗
PubMedDate not supplied

The use of dissimilar progressives in the management of presbyopia.

The management of anisophoria with bifocal spectacle correction has always presented a challenging refractive problem. Historically, practitioners have used dissimilar bifocal segments or bicentric grinding to neutralize induced vertical imbalance. We present a method of reducing anisophoria at near point with dissimilar progressive multifocals. By incorporating different progressive designs, anisophoria can be minimized to a tolerable level, based on the dioptric power of lens and progressive lens design.

Adult↗
PubMed2001

Scleral expansion bands for presbyopia.

OBJECTIVE: To evaluate the safety and effectiveness of surgery using scleral expansion bands. DESIGN: Prospective, noncomparative, small case series. PARTICIPANTS: Six subjects were enrolled. Four subjects received implants in one eye and two subjects received implants in both eyes. METHODS: Implantation of the scleral expansion bands (SEB) was performed using Schachar's standard technique. Subjects were observed at six postoperative examination intervals through 1 year. MAIN OUTCOME MEASURES: The key efficacy measures were distance-corrected near visual acuity (at 40 cm and 60 cm) and subjective amplitude of accommodation (push-up, push-down, and minus lens procedures). RESULTS: Distance visual acuity was similar before and after surgery. The near visual acuity and the subjective amplitude of accommodation were temporarily improved in three eyes. However, in the other five eyes, we did not note any improvement of accommodation or near vision after the scleral expansion surgery. CONCLUSIONS: In this study, the outcome of the SEB intervention was characterized by inconsistent and unpredictable results with a low level of patient satisfaction.

Accommodation, Ocular↗