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PubMed2006

[Presbyopia treatment using a femtosecond laser].

Presbyopia is by far the most common refractive error worldwide, with no permanent therapeutic option available. All efforts to restore accommodation by the use of surgery have not led to a generally accepted therapy. However, there is evidence from an animal model that the use of a femtosecond (fs) laser might influence the modulus of elasticity in the lens. Fs-laser impulses can create intralenticular disruption in animal eyes as well as human cadaver lenses and improve elasticity. The concept of treating presbyopia with fs-laser requires a new, complex theory combining the optical and the mechanical aspects of accommodation in the eye. Diagnostic tools for measuring optical change in power and geometrical modification as the eye views from far to near are needed to obtain objective clinical data. A non-invasive treatment of presbyopia to restore accommodation might be possible in the future.

Accommodation, Ocular↗
PubMed2002

The effect of incipient presbyopia on the correspondence between accommodation and vergence.

PURPOSE: To investigate the accommodation-convergence relationship during the incipient phase of presbyopia. The study aimed to differentiate between the current theories of presbyopia and to explore the mechanisms by which the oculomotor system compensates for the change in the accommodation-convergence relationship contingent on a declining amplitude of accommodation. METHODS: Using a Canon R-1 open-view autorefractor and a haploscope device, measurements were made of the stimulus and response accommodative convergence/accommodation ratios and the convergence accommodation/convergence ratio of 28 subjects aged 35-45 years at the commencement of the study. Amplitude of accommodation was assessed using a push-down technique. The measurements were repeated at 4-monthly intervals over a 2-year period. RESULTS: The results showed that with the decline in the amplitude of accommodation there is an increase in the accommodative convergence response per unit of accommodative response and a decrease in the convergence accommodation response per unit of convergence. CONCLUSIONS: The results of this study fail to support the Hess-Gullstrand theory of presbyopia in that the ciliary muscle effort required to produce a unit change in accommodation increases, rather than stays constant, with age. Data show that the near vision response is limited to the maximum vergence response that can be tolerated and, despite being within the amplitude of accommodation, a stimulus may still appear blurred because the vergence component determines the proportion of available accommodation utilised during near vision.

Accommodation, Ocular↗
PubMedDate not supplied

Presbyopia toward the end of the 20th century.

Recent advances in our understanding of the anatomy and physiology of accommodation have contributed to current concepts of the possible constituent factors in presbyopia, largely supplanting the long-held belief that presbyopia is due to sclerosis of the crystalline lens. In this review, the author examines epidemiologic, basic scientific, and clinical evidence for a multifactorial decrease in accommodative amplitude with age. Methods of measurement, oculomotor effects of presbyopia, and approaches to correcting it are also considered.

Accommodation, Ocular↗
PubMed2005

Presbyopia correction with an anterior chamber phakic multifocal intraocular lens.

PURPOSE: To investigate in a pilot study the potential of an anterior chamber phakic refractive multifocal intraocular lens (IOL) prototype for the correction of near and far vision in those with myopic and hyperopic presbyopia. DESIGN: A multicenter, open-label, prospective, noncomparative pilot evaluation. PARTICIPANTS: There were 17 patients (34 eyes), 16 women and 1 man, with a mean age of 52+/-3.94 years (range, 46-62 years). Six eyes were myopic (mean spherical equivalent [SE], -9.3+/-3.83 diopters (D)) and 28 were hyperopic (mean SE, +2.3+/-0.77 D), with astigmatism less than 1.5 D. METHODS: The prototype multifocal phakic IOL was implanted through a 6.5-mm temporal incision. The dominant eye was targeted for emmetropia and the nondominant eye for -1.0 D. MAIN OUTCOME MEASURES: The efficacy of the implant was assessed after surgery by measuring monocular and binocular uncorrected and distance-corrected visual acuity (VA) at distance, intermediate, and near, and distance-corrected near VA with near add. Distance-corrected distance and near VA also were determined in low contrast (25%). The safety index and efficacy index were calculated, and patient satisfaction questionnaires also were administered. Follow-up was at 1-3 days, 5-9 days, 21 days, 3 months, 6 months, and 1 year after surgery. RESULTS: Spherical equivalent refraction ranged from -11.75 to +4.25 D before surgery, and from -2.0 to +1.85 D 1 year after surgery. The binocular efficacy index was 0.68 (near) and 1.0 (distance), and the binocular safety index was 1.0 for both near and distance. Mean binocular uncorrected distance VA improved from 20/59 (+/-4 lines) before surgery to 20/18 (+/-1 line) 1 year after surgery. Mean binocular uncorrected intermediate VA improved from 20/125 (+/-10 lines) to 20/21 (+/-1 line), and mean binocular uncorrected near VA improved from 20/78 (+/-5 lines) to 20/32 (+/-1 line). Binocular uncorrected visual acuity was at least 20/40 (distance and intermediate) and Jaeger 3 in 88.2% of patients, and it was at least 20/40 and Jaeger 5 in 100% of patients. Patient satisfaction was very good in 88% of patients (15 of 17); the remaining 2 patients reported moderate satisfaction. CONCLUSIONS: Promising results were obtained with the refractive multifocal phakic IOL prototype investigated in this pilot study for near and far visual correction in presbyopia associated with myopia and hyperopia. Multifocal phakic intraocular optics may be an option for presbyopia correction.

Adult↗
PubMed2003

Presbyopia complicating pre-existing strabismus.

BACKGROUND: Presbyopia may affect pre-existing sensory adaptations or aggravate previously asymptomatic heterophoria. We describe the presentation, underlying problem and management of 11 patients with pre-existing strabismus or heterophoria who presented with new symptoms of double vision attributable to presbyopic change, an association not previously reported. METHODS: Patients with new strabismic symptoms attributable to presbyopia were recruited prospectively over a 1-year period. RESULTS: The 11 patients had had a recent decrease of accommodative amplitude that resulted in blurred vision at near with a breakdown of pre-existing heterophoria (2 patients), alteration of fixation pattern (6 patients), symptomatic alternating fixation (2 patients) or intolerance to correction owing to restrictive strabismus (1 patient). INTERPRETATION: At the onset of presbyopia, symptoms may be varied and subtle. Ophthalmologists and orthoptists should carefully determine the exact nature of the symptoms. Any pre-existing fixation pattern should then be established from the history, old photographs or suppression characteristics. Refractive or surgical management should be aimed at returning the patient to his or her long-standing sensory adaptation. Other important issues, such as incomplete correction of hypermetropia by refractive surgery and problems using bifocals with vertical restrictive strabismus, should be noted.

Accommodation, Ocular↗
PubMed1998

Static aspects of accommodation: age and presbyopia.

Although the progressive reduction in accommodative amplitude with increased age is well documented, little is known about several other aspects of static or steady-state accommodation to provide a comprehensive assessment of changes related to age and presbyopia. Static components of accommodation (tonic accommodation, depth-of-focus, slope of the stimulus/response function, and accommodative controller gain) were assessed objectively using an infrared (IR) optometer in 30 human subjects aged 21-50 years; depth-of-focus was also determined psychophysically as was accommodative amplitude. Tonic accommodation and the amplitude of accommodation decreased with increased age, whereas the subjective depth-of-focus increased; the other parameters remained unchanged. The decrease in tonic accommodation and amplitude of accommodation was attributed to biomechanical factors, whereas the increase in subjective depth-of-focus was believed to result from increased tolerance to defocus related to the gradual onset of presbyopia. Constancy of the objective depth-of-focus suggested absence of age effects on the neurologic control of reflex accommodation, whereas the lack of systematic change in slope and controller gain provided support for the Hess-Gullstrand theory of accommodation and presbyopia.

Accommodation, Ocular↗
PubMed1988

The mechanics of accommodation in relation to presbyopia.

The cause of presbyopia is closely related to the force of contraction of the ciliary muscle and the resistance to deformation of the crystalline lens. Two views are currently in conflict. The view of Donders (1864) that presbyopia is caused by a decrease in the force of contraction of the ciliary muscle with age, and the opposing view of Helmholtz (1855) that the lens becomes more difficult to deform with age due to lenticular sclerosis. The present paper shows that, in fact, the ciliary muscle undergoes a compensatory hypertrophy as accommodative amplitude decreases with age. The force of contraction is about 50% greater at the onset of presbyopia than in youth. However, because of increased lenticular resistance its effect on the amplitude of accommodation is small. It is shown that the reason the lens becomes more difficult to deform is not because of lenticular sclerosis, since the lens substance does not lose water. The increased difficulty of deformation is because the capsule loses its elastic force with age and the lens fibres, particularly in the nucleus, become more compacted.

Accommodation, Ocular↗
PubMed1998

[Effects of presbyopia on clinical phoria].

BACKGROUND: Due to accommodation-vergence cross-link we can expect that presbyopia will affect vergence as well. From investigations of cross-link as function of age one may assess strain of visual system due to presbyopia. Furthermore, this observation will give hints on innervation of ciliary muscle. MATERIAL AND METHOD: Vergence is assessed as function of stimulus of accommodation in 27 subjects (24-65 years). RESULTS: Presbyops tend to be exophoric for near vision. Vergence is linked to accommodation by means of a quadratic polynome rather than by a linear function. CONCLUSIONS: We may expect, that missing vergence strains visual system of presbyops. Results support Hess-Gullstrand theory of presbyopia and indicate a loss of innervation of ciliary muscle with increasing age.

Accommodation, Ocular↗
PubMed1994

Presbyopia and velocity of sound in the lens.

The elastic properties of lens matter change with age and this contributes to presbyopia. The changes in elasticity of lens matter could be the result of a change in water and soluble proteins (1) or a change in lens fiber cytoskeleton and membranes (2). If it is caused by (1) then the velocity of sound in the lens should change with age. If it is caused by (2) the velocity of sound in the lens will not change. Using the technique of continuous ultrasonographic biometry, the velocity of sound in clear lenses was measured in vivo in a group of 24 healthy subjects aged 15 to 45 years with a visual acuity of 6/6 or better. In this group maximum accommodative amplitude decreased with age. It was found that, despite the occurrence of presbyopia, the velocity of sound did not change with age. Our results support the hypothesis that age-related changes in lens fiber cytoskeleton and membranes are responsible for the change in elastic properties of lens matter and thus contribute to presbyopia.

Accommodation, Ocular↗
PubMed1998

Assessment of vergence facility in a sample of older adults with presbyopia.

PURPOSE: The aim of this study was to establish whether assessment of vergence facility is clinically useful in older adults with presbyopia and to determine pilot normative data for this age range. METHODS: Vergence facility was measured in a sample of 50 asymptomatic subjects with a mean age of 58.7 years using 8delta base-in (BI) and 12delta base-out (BO) prisms mounted in clinical flipper frames. Testing was performed for 1 min on four separate occasions over the course of a few weeks. RESULTS: Of the 42 subjects that completed the study, vergence facility could be satisfactorily measured on only 21 subjects. The mean vergence facility for this group was approximately 7 cycles per minute (cpm), commensurate with previous results in younger subjects using a similar paradigm. There were no differences in vergence facility between the first and second 30-s periods of testing, nor were there any differences in average vergence facility over the 4 test occasions. Test-retest repeatability, however, was poor. The BI prism phase took longer, on average, to fuse than the BO prism phase (BI 5.2 s and BO 3.7 s). CONCLUSIONS: Our results show a high degree of variability in vergence facility in older subjects with presbyopia. More research is required before deciding whether measurements of vergence facility are of use in investigating binocular vision of older patients with presbyopia.

Accommodation, Ocular↗
PubMed2004

Surgical treatment of presbyopia: scleral, corneal, and lenticular.

PURPOSE OF REVIEW: Having solved most of the problems concerning myopia, hyperopia, and astigmatism, it is perfectly understandable that the surgical treatment of presbyopia should be next on the agenda. It is a new challenge where every possible aspect is explored. RECENT FINDINGS: The past five years have been troubled by the debate over von Helmholtz theory on accommodation. Numerous investigations have been carried out on the primate and humans using various procedures. The more we learn about this mechanism, the nearer we will be to finding a solution to presbyopia. It appears essential to refer to recent works confirming von Helmholtz theory. Therefore, understanding presbyopia requires a great deal of optical ingenuity such as monovision, scleral modifications, which still remain controversial, or clear lens exchange or refilling. SUMMARY: In 2003, with all the different techniques available, the surgeon has a wide choice to offer patients that are satisfactory from a practical, theoretical, and ethical point of view. However, these techniques must only be proposed once the patients have been carefully informed.

Cornea↗
PubMedDate not supplied

Excimer laser photorefractive keratectomy for presbyopia: 24-month follow-up in three eyes.

BACKGROUND: For some patients, standard optical correction for presbyopia is not satisfactory. Using a specially designed mask, we developed a procedure for correcting presbyopia with excimer laser photorefractive keratectomy (PRK). METHODS: A mask consisting of a mobile diaphragm formed by two blunt blades was used to ablate a 10 to 17 microm deep semilunar-shaped zone immediately below the pupillary center, steepening the corneal curvature in that area. Three eyes of three presbyopic patients were treated, aiming at a near addition of +3.00 D. Follow-up time was 24 months. RESULTS: After an initial regression of 1.00 D during the first 6 months, the presbyopic correction remained stable for the duration of the follow-up period, enabling uncorrected near vision of J3 in all three eyes. Uncorrected distance visual acuity was not altered. Contrast sensitivity (Regan) was slightly decreased only at the 11% level. Videokeratography confirmed corneal steepening in the ablated area. CONCLUSION: The visual and refractive outcome of excimer laser PRK for presbyopia with the Aesculap-Meditec MEL 60 is promising, especially in view of the 2-year follow-up.

Cornea↗
PubMedDate not supplied

Advanced surface ablation for presbyopia using the Nidek EC-5000 laser.

PURPOSE: To present 1 to 6-month follow-up results of laser in situ keratomileusis (LASIK) using multizone presbyopic advanced surface ablation (PASA) with a peripheral near zone. METHODS: LASIK was performed on 28 eyes of 17 patients (10 men and 7 women; mean age 49.8 years with a range of 37 to 62 years). Eyes had primary or enhancement treatments with the Nidek EC-5000 excimer laser. Three techniques were used: 1) total transepithelial ablation, 2) surface ablation for far vision ametropia correction, and 3) concentric peripheral near zone presbyopia correction (technique developed by Dr. A. Telandro with a modified nomogram by Dr. R. Cantú for surface ablation). One surgeon (RC) performed all surgery. RESULTS: We present the preoperative and postoperative measurements for far and near uncorrected visual acuity, total high order aberrations, spherical aberration (Z-12), asphericity Q index, eccentricity corneal shape factor, and total coma and trefoil aberrations. Increases occurred in negative spherical aberration, negative asphericity index, and positive eccentricity corneal shape factor. CONCLUSIONS: Advanced surface ablation for presbyopia with a concentric peripheral near zone is a promising approach for surgical correction of presbyopia and potentially could be used with any advanced surface ablation procedure. Increases in negative spherical aberration and asphericity/ eccentricity indices seemed to increase the depth of focus of the eye, improving the near vision.

Adult↗
PubMed2001

[Physiopathology in accommodation and presbyopia, clinical and surgical approach].

Accommodation is a complex of phenomena by which the refracting power of the eye changes for focusing on near vision. Accommodative amplitude declines progressively with increasing age. Until today, this phenomenon called presbyopia was explained by Helmholtz's hypothezis which involves only ciliary muscle. It seems that in accommodation are involved, besides the ciliary muscle, the lens and extraventicular elastic components, biophysical dynamics of the lens capsule, vitreous, iris. According with the role of these factors and theirs pathophysiological implications, new surgical technique has developed to reverse presbyopia in the human eye (Surgical reversal presbyopia, Anterior ciliary sclerotomy) and offers a potential for understanding ocular hypertension and treatment of primary open-angle glaucoma.

Accommodation, Ocular↗
PubMed2005

Optics of conductive keratoplasty: implications for presbyopia management.

PURPOSE: To define the corneal optics of conductive keratoplasty (CK) and assess the clinical implications for hyperopia and presbyopia management. METHODS: Four analyses were done. (1) Multifocal effects: In a prospective study of CK, uncorrected visual acuity (UCVA) for a given refractive error in 72 postoperative eyes was compared to control eyes. (2) Surgically induced astigmatism (SIA): 203 eyes were analyzed for magnitude and axis of SIA. (3) Higher-order optical aberrations: Corneal higher-order optical aberrations were assessed for 36 eyes after CK and a similar patient population after hyperopic laser in situ keratomileusis (LASIK). (4) Presbyopia clinical trial: Visual acuity, refractive result, and patient questionnaires were analyzed for 150 subjects in a prospective, multicenter clinical trial of presbyopia management with CK. RESULTS: (1) 63% and 82% of eyes after CK had better UCVA at distance and near, respectively, than controls. (2) The mean SIA was 0.23 diopter (D) steepening at 175 degrees (P < .001); mean magnitude was 0.66 D (SD, 0.43 D). (3) After CK, composite fourth- and sixth-order spherical aberration increased; change in (Z12) spherical aberration alone was not statistically significant. When compared to hyperopic LASIK, there was a statistically significant increase in composite fourth- and sixth-order spherical aberration (P < .01) and spherical aberration (Z12) alone (P < .02); spherical aberration change was more prolate after CK. (4) After the CK monovision procedure, 80% of patients had J3 or better binocular UCVA at near; 84% of patients were satisfied. Satisfaction was associated with near UCVA of J3 or better in the monovision eye (P = .001) and subjectively good postoperative depth perception (P = .038). CONCLUSIONS: CK seems to produce functional corneal multifocality with definable introduction of SIA and higher-order optical aberrations, and development of a more prolate corneal contour. These optical factors may militate toward improved near vision function.

Adult↗
PubMed2003

Presbyopia among normal individuals.

BACKGROUND: To define ocular variables that might affect the need for early use of reading glasses. METHODS: A retrospective, non-randomized clinical trial was conducted at an aero-medical center. The charts of 100 healthy male pilots who suffered from presbyopia were reviewed. All subjects had undergone a complete eye examination every year for 30 years. Ocular parameters measured at the ages of 20, 30, 40, 45, and 50 years were recorded. Individuals were divided into two groups: those who needed reading glasses at the age of 45 years or earlier (group 1) and those who had needed reading glasses after 45 years of age (group 2). RESULTS: Of all the ocular variables examined each year, two differed significantly between the two groups. Refraction at age 20 was 0.1+/- 0.3 D in group 1 and 0.0 +/- 0.3 D in group 2 ( P <0.05). Amplitude of accommodation at age 20 was 9.5 +/- 1.2 D in group 1 and 9.9 +/- 1.0 D in group 2 ( P <0.05). CONCLUSION: Hyperopia and low amplitude of accommodation at the age of 20 might predispose to early development of presbyopia in normal individuals.

Accommodation, Ocular↗
PubMed2005

Esotropia associated with early presbyopia caused by inappropriate muscle length adaptation.

BACKGROUND: The purpose of this study is to investigate the occurrence of esotropia accompanying early presbyopia. The two primary long-term mechanisms for maintenance of ocular alignment are vergence adaptation (neurologic) and muscle length adaptation (anatomic). Both mechanisms depend upon disparity-driven motor fusion for proper operation. A possible cause for an esotropic shift in early presbyopic adults with insufficient or absent disparity-driven motor fusion is inappropriate muscle length adaptation (medial rectus muscle shortening) occurring in response to increased convergence tonus accompanying increased accommodative effort. METHODS: Of 617 patients, age 10 and older who underwent surgery for esotropia during the period of 1980 to 1996, the age when the deviation occurred or worsened could be determined with confidence in 140. A plot was made of the number of these patients versus the age of onset of the deviation. This was compared with a similar plot of patients operated for exotropia. RESULTS: A statistically significant increase (P = 0.017) in the incidence of an esotropic shift in the age range from 30 to 50 years was found when compared with the incidence of an exotropic shift. CONCLUSION: If the postulated mechanism is correct, full correction of any hyperopia as well as prompt prescription of a reading add (or conversion to monovision correction) may help prevent further progression of small esodeviations accompanying early presbyopia.

Accommodation, Ocular↗
PubMed2004

Correction of presbyopia with refractive multifocal phakic intraocular lenses.

PURPOSE: To evaluate the efficacy of and specify the conditions required for implantation of an anterior chamber multifocal phakic intraocular lens (IOL) to correct presbyopia. SETTING: Monticelli Clinic, Marseilles, France. METHOD: Fifty-five eyes of 33 patients (21 women, 12 men) had implantation of a foldable anterior chamber multifocal phakic IOL. The initial refraction was between -5.00 diopters (D) and +5.00 D. The IOL had an addition of +2.50 D. An uncorrected distance acuity of 0.6 or better (decimal scale) and an uncorrected near acuity (Parinaud scale) of 3 or better (Parinaud 2 approximately equal to Jaeger 1) was considered a successful postoperative result. RESULTS: The mean follow-up was 42.6 weeks +/- 18 (SD). Postoperatively, the mean refraction was -0.12 +/- 0.51 D, the mean decimal uncorrected distance acuity was 0.78 +/- 0.20, and the mean Parinaud uncorrected near acuity was 2.3 +/- 0.6. Eighty-four percent of eyes achieved an uncorrected distance acuity of 0.60 or better and an uncorrected near acuity of Parinaud 3 or better. The IOL was explanted in 4 eyes for different, but essentially optical, reasons. No significant anatomic complications were observed. CONCLUSIONS: Implantation of an anterior chamber multifocal phakic IOL to correct presbyopia was effective and gave good predictability. The procedure is reversible in cases of patient intolerance to the IOL, unwanted optical phenomena, or complications. Strict inclusion criteria should be used for patient selection.

Aged↗