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PubMed1993

Radial keratotomy for myopia. American Academy of Ophthalmology.

The operation of radial keratotomy is undergoing evolution and development. A few hundred thousand radial keratotomy procedures have been performed during the past decade by approximately 10% of the ophthalmologists in the United States. Clinical and laboratory data have now defined a relative level of safety and effectiveness for the procedure. Published data indicate that radial keratotomy usually achieves partial improvement in uncorrected visual acuity in patients with non-progressive low and moderate amounts of myopia. Undercorrection occurs commonly, and the amount of correction cannot be predicted accurately for an individual patient. Overcorrection occurs less often using four incisions. The unpredictability of the refractive outcome stems from several factors, including: 1) the biologic variability from one individual to another, 2) variation in surgical techniques among surgeons, 3) difficulty in making all incisions uniformly, and 4) inability to measure and control the biomechanical properties of the cornea. This is probably why there is not unanimity among radial keratotomy surgeons regarding the most effective surgical technique. Improvements in the surgery are occurring, including the use of staged, titrated techniques, and some series of radial keratotomy cases have reported better uniformity and predictability of outcome. The potential of this procedure to render good visual acuity without glasses or contact lenses must be weighed against its known risks. Refractive side effects include anisometropia (imbalanced vision between the two eyes), increased astigmatism, and symptomatic presbyopia (loss of near focus in middle life). Other common, usually less severe side effects include prolonged unstable vision and mild glare. Uncommon, but potentially binding, complications include ocular infection and traumatic rupture of the cornea at the keratotomy scars. The goal of radial keratotomy is to correct the refractive error of myopia. It also may serve to improve cosmetic appearance if the patient does not require glasses after surgery. It is elective surgery because other alternatives are available for the management of myopia, including conventional glasses and contact lenses. In addition, other refractive keratoplasty procedures are available, including excimer laser photorefractive keratectomy, keratomileusis and epikeratoplasty. Selection of the best alternative for the management of myopia in an individual patient should be based on the patient's personal needs and on the ophthalmologist's and patient's assessment of the risks and benefits of the available modes of correction.

Humans↗
PubMedDate not supplied

[The treatment of myopia by photoreactive keratectomy (PRK) with the 193-nm excimer laser].

Excimer laser photokeratectomy is the most recent procedure used for correcting myopia surgically. It consist in flattening the cornea by performing ablations of a part of its anterior stroma. Over 15,000 patients underwent this almost entirely robotic surgical intervention, supposed not to present the shortcomings of radial keratotomy. This robotic surgery tend to replace radial keratotomy. Photokeratectomy is designed to correct all kinds of myopia, astigmatism as well as these resulting from such surgical interventions as cataract extraction or Keratoplasty. A bifocal photorefractive keratectomy is expected to correct the myopia of the patients who reached the age of presbyopia.

Animals↗
PubMed1995

The fluctuations of accommodation and ageing.

OBJECTIVE: The aim of this study was to investigate the influence of age on the fluctuations of accommodation. METHOD: Fluctuations of accommodation were measured on six 'young' (16-25 years, mean age 22 years) observers and six 'older' (35-48 years, mean age 42 years) observers. Accommodation was continuously recorded using a SRI optometer whilst the observers steadily viewed a high contrast target at stimulus levels 0.25 D, 1.00 D and 2.00 D. Fluctuations were quantified using power spectrum analysis, and frequencies were grouped into bands: low (LFC 0.3-0.6 Hz and 0.3-0.9 Hz) and high (HFC 1.1-2.2 Hz). RESULTS: Accommodation response levels for these stimuli for both groups of observers were quite similar. Fourier analysis was used to generate power spectra so that the fluctuations of accommodation for each observer group could be compared. In general power increased for increasing response levels for both groups of observers, although less power was evident for the older observers in both LFC and HFC bands. Differences in power were not significant at these frequency bands for the two observer groups. When the whole power spectrum is compared these differences became significant with more power evident in the younger cohort. CONCLUSION: Reductions in both amplitude and speed of accommodation with age are well known, and the decline in magnitude of the fluctuations found here is consistent with a general diminution in accommodation dynamics as the accommodation mechanism ages. For the older group, some of who were near absolute presbyopia, there may be little contribution to power from changes in lens shape and it is possible that small changes in lens position in the eye contribute to the power spectrum.

Accommodation, Ocular↗
PubMed1995

Effect of age on the interaction between the AC/A and CA/C ratios.

A number of previous studies have examined the effects of age and the development of presbyopia on either the accommodative convergence to accommodation (AC/A) or convergent accommodation to convergence (CA/C) ratios. However, changes in the interaction of these oculomotor crosslinks with increasing age have received relatively little attention, especially over a wide age distribution. Accordingly, the present study examined both crosslink ratios in 42 subjects ranging from 22 to 65 years of age. A dual haploscope-optometer was used to measure accommodation and vergence. The response AC/A ratio showed a small but significant positive correlation with age in those subjects under 45 years of age, while no significant correlation was observed between the stimulus AC/A ratio and age for all subjects. The CA/C ratio exhibited a significant negative correlation with age for all subjects. Furthermore, a trend was observed for lower CA/C findings to be associated with higher response AC/A ratios. However, the two ratios were inversely but not reciprocally related, with the mean difference between the CA/C ratio and the reciprocal of the response AC/A ratio being significantly different from zero. These age-related changes in the output of the oculomotor crosslinks provide further evidence of the continual oculomotor adaptation that occurs concurrent with the loss of accommodative responsivity.

Accommodation, Ocular↗
PubMed1977

How aging affects the ear.

With aging, a different variety of ear diseases becomes more common. External ear disease is often a local reflection of generalized skin problems aggravated by retained water or local manipulation. Hearing loss may be the result of long-standing middle ear disease rather than aging. In this situation, the inconveniences and possible dangers of a chronically infected ear may be resolved with surgical intervention. Nasopharyngeal or lymphomatous disease must be suspected in any geriatric patient manifesting middle ear disease for the first time. Like presbyopia, presbycusis is a normal consequence of aging. It may be severe, but it does not lead to total deafness and equally involves both ears. Early discovery of the condition and institution of hearing rehabilitation methods will minimize the individual's communicative handicap and tendency to withdraw from society. Unilateral or asymmetric sensorineural hearing loss should be thoroughly evaluated for the purpose of identifying a curable and potentially life-threatening disease.

Aged↗
PubMed1996

Comparative double blind multicentric randomised placebo controlled clinical trial of a herbal preparation of eye drops in some ocular ailments.

A double masked placebo controlled multicentric randomised clinical trial was conducted in 157 patients suffering from different eye ailments namely, cataract, dry eye syndrome, ocular asthenia, refractive errors and allergic conjunctivitis with a herbal eye drop preparation and placebo. In both dry eye syndrome and ocular asthenia the herbal eye drop preparation was found better than placebo. In a few cases of cataract, the vision seems to be improved. In early myopia it seems to correct the refractive errors while in high myopic conditions it controlled the progressive deteriorations. Subjective improvements were also noted with hypermetropia, presbyopia and astigmatism. Its healing capacity in allergic conjunctivitis was certainly better than placebo. It had no short term or long term side-effects. It is considered to be a useful drug in all conditions studied.

Double-Blind Method↗
PubMed1996

Prospective clinical evaluation of Sunsoft Multifocal contact lens.

PURPOSE: We conducted a 3-month prospective clinical study to evaluate the clinical performance of the Sunsoft Multifocal contact lens as well as to determine the subjective factors that influence the decision to purchase a multifocal soft contact lens for the correction of presbyopia. METHODS: In this study, 215 patients at 16 sites were initially fit with the Sunsoft Multifocal contact lens. At 1 month, 179 patients were still wearing the lens successfully. Slit lamp evaluation of lens-cornea relationship, any change in ocular surface characteristics from initial fitting, and visual acuities were recorded at 1-month and 3-month follow-up visits. At the 1-month visit, patients completed evaluation forms to rate their perceptions of handling, comfort, visual performance, overall satisfaction, and whether they would purchase the lens if given the opportunity. RESULTS: Most patients who would choose to purchase lenses (80%) were in the group that achieved 20/25 or better binocular acuity both at distance and at near. Statistical analysis of all patients showed no difference in age, refractive error, comfort, handling, or near addition between those who would or would not purchase lenses; however, there was a significantly smaller monocular acuity imbalance in the purchase group. Analyzing just that subgroup of the population with 20/25 or better vision, the statistical analysis again showed the difference was in the binocularity of the patients. The closer together the right and left eye were in absolute acuity, the more likely the patients were to be satisfied with their lenses. There were no adverse reactions and the most common reason for failure to complete the study was inadequate near vision. CONCLUSIONS: This study yielded valuable insight into the performance of the Sunsoft Multifocal as well as those factors that influence the purchase of a soft hydrogel multifocal option.

Adult↗
PubMed1996

Refractive problems of the eye.

Refractive problems of the eye are common. About 25% of adults have detectable myopia, or short-sightedness. Hypermetropia, or long-sightedness, is even more common, with one study estimating about 50% of adults affected. The actual number that have symptomatic refractive problems is far smaller, with about 10% of people needing refractive correction for myopia. The authors give an overview of the common refractive problems of myopia, hypermetropia, presbyopia and astigmatism.

Adult↗
PubMed1996

Night myopia and driving.

Current knowledge of the refractive shifts (twilight myopia, night myopia, dark focus) that occur as the luminance is progressively lowered from photopic levels is reviewed. In complete darkness, myopic changes of the order of 1 dioptre are typical in young adult subjects. These gradually diminish as presbyopia is approached. The possible role of these refractive changes in causing visual difficulties for young drivers on the road at night is considered. It is concluded that high mesopic levels (about 1 cd/m2) of road luminance produced by street and vehicle lighting are normally too great to allow significant refractive shifts to occur, although acuity will be reduced due to light-dependent neural changes. Under these circumstances it appears unlikely that specific night-driving prescriptions will be beneficial: the accurate correction of normal refractive errors is, however, more important during night than day driving due to the greater blur associated with the larger night-time pupil. Suggestions are made for further experimental work in this area.

Accommodation, Ocular↗
PubMed1997

Cornea-contact lens interaction in the aquatic environment.

PURPOSE: A large population of ametropic scuba divers wear contact lenses. We discuss optics and corneal physiology, as well as the types of contact lenses that are appropriate for underwater activities. METHODS: We reviewed an extensive body of literature to formulate guidelines to aid the contact lens fitter in satisfying individual sport diver's needs. RESULTS: Optical factors such as image displacement and light wave-length shifts require that contact lenses for underwater use be suitably modified. Underwater images appear nearer and larger (requiring greater accommodation) and are made up almost exclusively of the short wavelength end of the spectrum. Correction of presbyopia, in particular, is influenced by these factors. For example, presbyopic contact lens-corrected myopes require greater near adds underwater than when viewing the same objects in air. In general, presbyopes should consider monovision correction to facilitate underwater visual tasks. Although divers wearing rigid gas permeable contact lenses run the risk of more corneal problems than soft lens wearers if conservative ascents are not adhered to, there are no compelling reasons to change lens types in patients who are already fully adapted. Soft contacts, while very stable on the eye during diving, present a greater risk of lens contamination by sea or fresh water exposure. However, the latter problems are easily overcome by using disposable soft lenses. CONCLUSION: In this paper, we present several suggestions for lens material, modifications required for underwater ametropia correction, and wearing modalities for the sport divers. An understanding of the dramatic changes that impact the properties of light, corneal physiology, and visual perception which accompany the diver below the surface will enable the contact lens fitter to design a lens appropriate to the needs of the individual patient.

Contact Lenses, Hydrophilic↗
PubMed1997

Vision screening in older adults on dialysis: do nephrology nurses have a role?

Undetected vision loss commonly occurs in older adults adding undue stress to those on dialysis. Poor vision is associated with increased risk of falls and decreased quality of life. Common visual impairments--presbyopia, cataracts, age-related macular degeneration, glaucoma, and diabetic retinopathy--often are detectable by visual acuity testing. Using various methods of visual acuity testing, nephrology nurses can perform vision testing quickly and inexpensively. Other nursing interventions also can improve eyesight.

Aged↗
PubMed1976

New aspects of contact lenses in ophthalmology.

The introduction of the hydrophilic contact lens has been a significant advance in ophthalmology for the correction of ametropia, as well as for the therapy of corneal disease. The number of potential contact lens candidates has been greatly expanded by the introduction of both spin-cast and lathe-cut lenses composed of a variety of individual hydrophilic polymers. Myopia, hyperopia, presbyopia, aphakia and moderate astigmatism can be corrected with a reasonable degree of success with the present lenses. Even in keratoconus hydrophilic lenses offer a nonsurgical alternative, especially when combined with spectacle overcorrection. The introduction of hydrophilic bandages in the treatment of corneal disease has been an important addition to the therapeutic armamentarium of the ophthalmologist. When properly applied, these lenses can provide subjective relief of pain while serving to protect the damaged cornea from the traumatic action of the lids and desiccating effects of the atmosphere. The hydrophilic material is permeable to many topically instilled medications and tends to prolong the contact time of the drugs with the corneal surface. Proper fitting of the bandage lenses can eliminate superficial corneal irregularities and, thus, improve the visual acuity while treatment progresses. Medical indications for the use of this therapy include bullous keratopathy, dry eye syndromes, chemical burns, exposure keratitis, and neurotropic keratitis. A number of recurrent erosions and ulcerations have also responded to this form of therapy. Surgical indications include lacerations, postoperative lamellar and penetrating keratoplasty, and keratectomies. One of the most promising applications concerns their use in the postoperative management of alkaline burns. Best results have been obtained by constant wear of the bandage lens, with topical administration of steroids, antibiotics, and saline solution (hypotonic or hypertonic) as indicated. The possible deleterious effects of standard ocular medication containing preservatives has been overstated. Patients receiving medications without preservatives must be placed on prophylactic antibiotics to avoid secondary infection. In many cases, the therapeutic efficacy is closely related to the diameter and curvature of the bandage lens as well as the inherent physical properties of the polymers. With meticulous fitting and close observation complications have been minimal. In many instances the results have been dramatic, but even if unsuccessful the method provides a safe and relatively simple nonsurgical alternative in the treatment of severe corneal disease. Just as with older modalities, the ultimate success or failure depends upon the intrinsic nature of the disease process as well as reasonable therapeutic application based on a knowledge of the mechanics involved.

Chemical Phenomena↗
PubMed1997

An overview on management of the traumatised elderly patient.

The elderly are predisposed to injuries due to consequences of ageing and presence of disease process commonly seen in the old people. Age-related deterioration of senses such as decrease in hearing capacity, presbyopia, changes in co-ordination, balance, motor strength and postural stability render the elderly vulnerable to environmental hazards. Diseases such as dementia, congestive cardiac failure, postural hypotension, osteoporosis and arthritis further contribute to compound problems of the elderly. Age and chronic factors further blunt the reserves to enable an elderly individual meet the demands of trauma. The challenge to the clinician is to be aware of the subtle changes and deviation from the norm that may suggest development of complications. With careful attention and appropriate physiological support the elderly patient has a good chance of survival. The primary condition must be assessed, necrotic tissues must be debrided by thorough surgical toileting, pus must be drained, wounds sutured and fractures must be set while cardiopulmonary activity must be monitored accurately. The patient should be re-assured, kept warm and adequate analgesia given to relieve pain. Intravascular volume and composition of extracellular fluid must be maintained. Nutritional support should be provided in amounts needed to meet the higher demands of trauma and preferably by oral feeding. Above all multidisciplinary approach to the traumatised elderly is mandatory involving surgeons, physicians, physiotherapists and other paramedical staff and relatives.

Aged↗
PubMed1998

[Pure alexia: presentation of a case].

INTRODUCTION AND CLINICAL CASE: A case of pure alexia, secondary to an occipital cerebral infarct, is presented, which initially appearing with bilateral amaurosis of two hours of duration, following by a significant difficulty to read, and according to patient, was a deficit to near vision and by criteria of ophthalmologists and optometrists was a presbyopia. Authors identified a lack of P-300 wave in study of endogenous component of events related potentials (ERP), to task of phonetic discrimination, and its normal registry to task of graphic discrimination. CONCLUSION: Therefore, we confirm the cliniconeurophysiologic diagnosis of a pure alexia without agraphia, by means of this non-invasive method studying cerebral cognitive process.

Cerebral Infarction↗