Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PRESBYOPIA”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources
PubMed2002

Anterior ciliary sclerotomy for treatment of presbyopia: a prospective controlled study.

PURPOSE: To examine the safety and efficacy of anterior ciliary sclerotomy to restore accommodation in the presbyopic eye. DESIGN: Prospective nonrandomized comparative single-center clinical trial. PARTICIPANTS: Nine presbyopic subjects with no prior ocular surgery except corneal refractive procedures were enrolled. METHODS: One eye from each subject was chosen, in consultation with the patient, to undergo anterior ciliary sclerotomy. The contralateral eye of each subject served as a control. Examinations were performed preoperatively, and at 1 day, 1 week, 1 month, and 6 months after surgery. MAIN OUTCOME MEASURES: (1) Accommodative amplitude, measured by two methods, (2) Jaeger reading vision at 14 inches wearing best distance correction, (3) manifest refraction, (4) assessment of operative complications. RESULTS: For the nine study eyes, there was no statistically significant change between the average accommodative amplitude at the preoperative visit (1.11 diopter [D]) and the 1-month postoperative visit (1.19 D, P = 0.55) nor at the 6-month postoperative visit (1.31 D, P = 0.21) in the study eyes. There was no significant difference between the study and control eyes' change in accommodative amplitude at 6 months (P = 0.43). Logarithm of the minimum angle of resolution equivalent of Jaeger reading vision in the study eyes at 14 inches wearing best distance correction showed no statistically significant change from the preoperative visit (0.53 [20/70]) at the 1-month postoperative visit (0.41 [20/50], P = 0.07) or at the 6-month postoperative visit (0.48 [20/60], P = 0.22). There was no significant change in manifest refraction spherical equivalent in the study eyes at 1 and 6 months postoperatively. One eye experienced a perforation of the anterior chamber during surgery. A second eye experienced mild postoperative anterior segment ischemia manifested by sectoral iris akinesis. CONCLUSIONS: Anterior ciliary sclerotomy does not restore accommodation in presbyopic eyes and can cause significant complications.

Accommodation, Ocular↗
PubMed2002

Gender-related optical aspects of the onset of presbyopia.

Evidence is presented which substantiates the frequent clinical impression that female optometric patients require their first reading prescription at a slightly earlier age than males. Furthermore newly presbyopic females require an initial add of slightly greater magnitude than age-matched males. A high (>+1.50 D) first add requirement is revealed as a predominantly male characteristic, an outcome attributable essentially to their often relatively later age of presentation for an initial presbyopic refractive examination.

Age of Onset↗
PubMed2002

Modelling the mechanics of accommodation and presbyopia.

Finite element methods have been used to compute the expected relationship between changes in ciliary body diameter and the change in refractive power implied by the change in geometry of the human ocular lens, using values for the material properties and initial geometry taken from the literature (notably the slit lamp photography of Brown (1973) and the studies by Fisher (1969) of the lens material properties). The results show that if the non-linearity associated with the changing geometry is taken into account the lens does not respond to ciliary body stretch by an increase in power [as recently claimed by Schachar et al. (1993), but in the conventional way with a decrease in power. The models show a decrease in the amplitude of accommodation between the age of 29 and 45 years (using Brown's data, 1973), but using Brown's data for the 11-year-old eye leads to the paradoxical conclusion that accommodation amplitude in this eye would have been small. In the process of carrying out the modelling, we have examined the consistency of the published measurements and also the validity of the mathematical methods used in interpreting them, and this analysis suggests that further work is needed before one can be confident that the assumptions about geometry and material properties on which the modelling is based are sound.

Accommodation, Ocular↗
PubMed2003

The effects of wearing corrective lenses for presbyopia on distance vision.

The possibility of patient behaviour concerning the wearing of reading spectacles influencing the magnitude and rate of change in distance vision has been hypothesised but not fully examined. This study examined the changes in distance vision over time of 674 presbyopic patients between the ages of 44 and 69 who came to their eye professional needing reading spectacles. Prior to this study, these patients had never worn spectacles. The majority of patients opted for full-eye (complete) reading spectacles and 150 patients selected bifocals. It was found that patients wearing complete reading spectacles eventually adapted to wearing their reading spectacles for intermediate or distance work. Through X2, it was found that there were significant differences in the reduction of distance visual acuity between groups based on the amount of time spent wearing reading spectacles for intermediate or distance work. The greater the number of hours spent wearing reading spectacles and viewing beyond their focal point, the greater the change in distance visual acuity. It also appeared to affect the degree of change in their prescription. Age was not significantly related.

Accommodation, Ocular↗
PubMed1985

[Experimental studies on the correction of presbyopia].

As a consequence of the changing population structure the number of older, i.e., presbyopic people in work will increase in the future. At the same time the demands made on vision at work will also increase, as new technologies are introduced. Both of these factors will have to be taken into account by ophthalmologists and the optical industry. As accommodation deteriorates, special glasses become necessary which are suited to requirements for highly qualified work. With this in mind the authors conducted a joint investigation at a precision assembly workplace together with the manufacturing technology laboratory of Duisburg University. The results show that if bifocal or respectively trifocal glasses are prescribed at the right time efficiency can be improved both quantitatively and qualitatively. The specific requirements with regard to spectacles worn at such workplaces result in particular from the fact that, for ergonomic and technical reasons, operating devices and controls are being mounted ever more frequently above the horizontal line of gaze. Therefore, when prescribing the glasses, it is important that not only the correction for close and mid-range vision, but also the size and location of this portion of the lens should be taken into consideration. This is illustrated with a number of examples.

Adult↗
PubMed2001

Hydrogels as potential probes for investigating the mechanism of lenticular presbyopia.

PURPOSE: To synthesize and characterize hydrogels with viscoelastic properties comparable to those of the natural lens. METHODS: Hydrogels were synthesized in water by free-radical polymerization of the monomer poly(ethyleneglycol)-monomethacrylate. Three different molecular weights of poly(ethyleneglycol)-dimethacrylates were used as crosslinkers. For each crosslinker used, five different monomer-to-crosslinker weight ratios were utilized while the total mass of the reactants was kept constant. In another series, the concentration of the reactants was varied while the weight ratio of monomer to crosslinker was kept constant at 95 : 5. The percent optical transmission, equilibrium water content, moduli (elastic, shear, storage, and loss), and retardation time constant of the hydrogels were determined. In addition, endocapsular polymerization was performed in the capsular bag of porcine eyes. RESULTS: The hydrogels examined exhibited the following ranges for viscoelastic properties: elastic modulus, 1.33-2.37 x 10(4) Pa; shear modulus, 3.35-6.72 x 10(3) Pa; storage modulus, 1.65-6.24 x 10(4) Pa. For any given hydrogel, raising its crosslinker's weight ratio increased its moduli and decreased its equilibrium water content and optical transmission. For any given monomer-to-crosslinker weight ratio, increasing the molecular weight of the crosslinker reversed these trends. Reactant concentrations increased the elastic modulus and decreased the equilibrium water content. The hydrogels formed ex vivo (in the evacuated capsular bag of porcine eyes) allowed for the clear and undistorted viewing of objects. CONCLUSIONS: Hydrogels that exhibit physical and mechanical properties comparable to those of the natural lens were successfully identified, synthesized, and characterized, and the feasibility of endocapsular polymerization was demonstrated.

Animals↗