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PubMedDate not supplied

Laser photocoagulation of choroidal neovascularization in pathologic myopia: long-term results.

Direct laser photocoagulation of macular choroidal neovascularization (CNV) in pathologic myopia is still controversial. However, previous studies have reported encouraging results. One-hundred and thirty-three consecutively treated eyes were followed, in a prospective manner, for at least 12 months (108 of these were followed for 24 months, 84 for 36 months, 63 for 48 months, and 47 for 60 months) to evaluate the potential benefits and complications of laser treatment of extra-foveal macular CNV in pathologically myopic eyes. Pre-treatment mean visual acuity was 0.36. Post-treatment mean visual acuity was 0.33 at 1-year examination, 0.31 at 2 years, 0.32 at 3 years, 0.34 at 4 years, and 0.33 at 5 years. During the total follow-up period mean visual acuity did not change. Neovascular recurrences occurred in 58% of treated eyes by the end of the five-year follow-up. At final examination, complete destruction of CNV was achieved in 100 eyes (75%). These findings suggest that laser photocoagulation of macular choroidal neovascularization in pathologic myopia may be effective in preventing or limiting severe and irreversible loss of vision.

Adult↗
PubMed1995

Nearwork-induced transient myopia: a critical review.

The literature on nearwork-induced transient myopia (NITM) is reviewed, with NITM being defined as the short-term myopic far point shift immediately following a sustained near visual task. A majority of these investigations demonstrated the presence of NITM for a variety of test parameters, e.g., visual acuity, contrast sensitivity and far point. Overall, these studies reported relatively small myopic shifts, with a mean of approximately 0.40 D and a range from 0.12 to 1.30 D. The subsequent decay is characterized by an exponential function with a relatively short time course. While the precise etiology and implications of NITM remain unclear, speculations regarding its origin and relevance to clinical myopia are discussed. Studies that did not demonstrate NITM are also reviewed.

Accommodation, Ocular↗
PubMed1979

Eyelid closure causes myopia in humans.

Humans with unilateral ptosis are more myopic in the closed eye than in the normal eye. The effect seems unrelated to visual loss. In pairs of humans ranked for sleep and myopia, the more myopic tends to sleep the more. We conclude that eyelid closure causes myopia.

Adolescent↗
PubMed2003

Multisensory enhancement of localization under conditions of induced myopia.

Enhanced behavioral performance mediated by multisensory stimuli has been shown using a variety of measures, including response times, orientation behaviors, and even simple stimulus detection. However, there has been little evidence for a multisensory-mediated improvement in stimulus localization. We suggest that this lack of effect may be a result of the high acuity of the visual system. To examine whether normal visual acuity may be masking any potential multisensory benefit for stimulus localization, we examined the ability of human subjects to localize visual, auditory and combined visual-auditory targets under conditions of normal and degraded vision. Under conditions of normal vision, localization precision (i.e., variability) was equivalent for visual and multisensory targets, and was significantly worse for auditory targets. In contrast, under conditions of induced myopia, visual localization performance was degraded by an average of 25%, while auditory localization performance was unaffected. However, during induced myopia, multisensory (i.e., visual-auditory) localization performance was significantly improved relative to visual performance. These results show a multisensory-mediated enhancement in human localization ability, and illustrate the cross-modal benefits that can be obtained when spatial information in one sense is compromised or ambiguous.

Acoustic Stimulation↗
PubMed2002

[Bioptic. A refractive surgery procedure for correction of high and extreme myopia].

BACKGROUND: The complete correction of highly or extremely myopic eyes to emmetropia can only be achieved by very few procedures: The combination of implanting phacic intraocular lenses and the use of LASIK (laser in-situ keratomileusis) - Bioptic - makes it possible to achieve this goal to a great extent. PATIENTS AND METHODS: The Bioptic procedure was carried out on 17 eyes of 10 patients. Two weeks after corneal dissection with the Hansatom,an implantable phacic lens (STAAR) was introduced into the posterior chamber and 4 weeks later the residual myopia was treated with LASIK combined with the correction of astigmatic errors. The follow-up time was 10.2 (6.7) months. RESULTS: Preoperative average values of the manifest refraction were -16.22 sph (3.86) with 1.40 cyl (1.30) which changed to -3.85 sph (2.73) with -1.50 cyl (0.87) after implantation of an ICL trade mark into the posterior chamber. Visual acuity increased from uncorrected hand motion to 0.13 (0.10) and corrected from 0.53 (0.19) to 0.63 (0.19). The refraction of implanted ICLs trade mark was 14.6 dpt (1.1). Following the LASIK procedure the uncorrected visual acuity improved to 0.68 (0.16) and fully corrected to 0.79 (0.20). The final refraction measured +0.16 sph (0.67) with -0.48 cyl (0.25). The keratectomy depth was 80.63 -m (26.9) and the optical zone showed a horizontal distance of 6.28 mm (0.39). CONCLUSION: Bioptic is able to correct highly and extremely myopic eyes with the combination of phacic lenses and subsequent LASIK. A concomitant astigmatism can be corrected up to 2.5 dpt simultaneously. With the combination of both procedures,the optical zone can be enlarged. Keeping in mind that phacic lenses reveal a constant refraction after a few days and also that LASIK is refractively safe in low myopia of -4 dpt to -5 dpt, it can be expected that the refractive deviation following the Bioptic procedure is low.

Astigmatism↗
PubMed2005

[LASIK using a scanning spot excimer laser for the treatment of myopia and myopic astigmatism 3-Jahresergebnisse].

PURPOSE: The correction of refractive errors using laser in situ keratomileusis (LASIK) has become the primary refractive procedure worldwide. The purpose of this study was to evaluate LASIK within a retrospective cohort. PATIENTS AND METHODS: The mean preoperative spherical equivalent for the 34 consecutively treated eyes was -6.67+/-2.69 D. The LASIK operations were performed by a Hansatome microkeratome (Bausch and Lomb) and a scanning spot excimer laser (Technolas Keracor 217, Bausch and Lomb). For pre- and postoperative analysis the Datagraph med software (Version 2.7) was used. RESULTS: None of the treated eyes lost 2 or more lines of best-corrected visual acuity (BCVA). At the 36-month examination the spherical equivalent had changed to -0.47 D (mean increase of myopia: 0.13 D). No long-term complications were found in the study period. CONCLUSION: LASIK with superior hinge and scanning spot excimer ablation is an effective treatment for the correction of myopia and myopic astigmatism in the refractive range described above.

Adolescent↗
PubMed1998

[Laser in situ keratomileusis (LASIK) for correction of myopia and astigmatism].

PATIENTS AND METHODS: In order to better define the potential advantages and risks of laser in situ keratomileusis (LASIK), we designed a prospective study including 73 eyes. RESULTS: After 6 months, 62 eyes were examined. Myopia was corrected from -6.10 +/- 3.12 (mean +/- standard deviation) to +0.04 +/- 0.66 D, with 54 eyes (87.1%) being within +/- 1.00 D of emmetropia. Astigmatism was corrected from -1.07 +/- 1.02 to -0.32 +/- 0.89 D. Uncorrected visual acuity was 0.5 or better in 59 eyes (95.2%) and 1.0 or better in 27 eyes (43.5%) 6 months postoperatively. More than one line in best-corrected visual acuity was lost by 6 eyes (9.7%), with most of these eyes being highly myopic. There was no change or a gain in lines in best corrected visual acuity in 42 eyes (66.1%). Intraoperative complications arose in two eyes (2.7%); in one eye, visual acuity was temporarily decreased. More treatments were performed in 7 eyes (9.6%). Postoperatively, no haze, scars or central islands were detected. Patient satisfaction after LASIK was high: 97.3% were pleased or very pleased with the result. CONCLUSIONS: In conclusion, LASIK is effective in the correction of myopia and myopic astigmatism. Although complications more frequently occurred in the correction of higher refractive errors, LASIK seems to be relatively safe compared with other refractive methods.

Adult↗
PubMed2001

[Results of implantation of a Worst Iris Claw Lens for correction of high myopia].

BACKGROUND: The purpose of this clinical study was to evaluate refraction, best visual acuity and anterior chamber flare after implantation of a Worst Iris Claw Lens to correct high myopia. PATIENTS AND METHODS: From September 1996 to February 1999 the implantation of a Worst Iris Claw lens was performed on 44 highly myopic phakic eyes of 28 patients. Data after 6 weeks and 6 months follow-up were assessed. RESULTS: The mean preoperative spherical equivalent was--17.35 +/- 3.57 dpt and 6 months after implantation 79% of the eyes were within +/- 1.0 dpt of target refraction. The mean best corrected visual acuity increased from 0.43 preoperatively to 0.65 postoperatively and 6 months after the treatment there was no flare (< 10 photons/ms) in 21% and a mild anterior chamber flare (10-80 photons/ms) in 76% of the treated eyes. The median laser flare was 20 p/ms. CONCLUSIONS: In conclusion, implantation of a Worst Iris Claw lens has proved to be a precise method to correct high myopia. No or mild anterior chamber flare and a good visual acuity were measured in most eyes 6 weeks and 6 months after surgery. Longer follow-up periods are needed to assess the long-term safety and efficiency.

Follow-Up Studies↗
PubMed2004

Corneal sensation after laser epithelial keratomileusis for the correction of myopia.

BACKGROUND: Subepithelial nerve fibre bundles and stromal nerves are damaged during laser epithelial keratomileusis (LASEK). The aim of this study was to investigate the recovery of corneal sensation after LASEK for the correction of myopia. METHODS: Corneal sensation was evaluated in 40 eyes of 20 patients using a Cochet-Bonnet aesthesiometer before surgery and 3 days, 14 days, 1, 3 and 6 months after LASEK for the correction of mild to moderate myopia (range -2.5 D to -8.0 D). At every examination corneal sensation was tested in the apex of the cornea and in one point each at the 12, 3, 6 and 9 o' clock positions 2 mm from the centre of the cornea. RESULTS: Corneal sensation was significantly reduced at 3 days and 14 days after surgery (P<0.01). The loss of corneal sensation was greatest 3 days after surgery and corneal sensation increased during the first month after LASEK. After 1 month, 3 months and 6 months no significant difference was found between preoperative and postoperative sensation. There was no significant difference in sensation between different areas of the cornea after LASEK. CONCLUSIONS: Corneal nerves are disrupted during LASEK surgery and the procedure results in a significant reduction in corneal sensation. During the first month after surgery the depressed corneal sensation improved and subsequently went back to preoperative values, staying stable 3 months and 6 months after surgery.

Adult↗
PubMed2006

Microcornea associated with myopia.

BACKGROUND: The presentation of microcornea associated with axial myopia by means of modern examination techniques. METHODS: Clinical investigations. RESULTS: The horizontal diameter of the cornea was 8.00 mm on both sides. The average refractive power of the cornea was 39.27D/38.48D on the right/left sides by corneal topography. The central corneal thickness was 568 micro m/559 micro m on the right and left sides, respectively. The depth of the anterior chamber was 1.18 mm/1.14 mm and the origin of the irises was steep, as demonstrated by ultrasound biomicroscopy (UBM). The axial length was 26.42 mm/25.63 mm on the right/left sides. Endothelial morphology disclosed degeneration on both sides. CONCLUSIONS: The present case demonstrates that the clinical signs of microcornea are flat corneal surface, normal thickness, and degenerated endothelium. This disorder associated with axial myopia is an extremely rare ophthalmologic condition.

Cornea↗
PubMedDate not supplied

Fundus characteristics of high myopia in children.

PURPOSE: To evaluate the fundus characteristics of highly myopic eyes in children. METHODS: We reviewed the medical records of 46 children (1 to 8 years old; mean age, 6.8 years) (80 eyes) with high myopia (4 D or more for children younger than 5 years, 6 D or more for children aged 6-8 years) seen consecutively during a 10-year period at the high-myopia clinic in our hospital. Children of up to 8 years of age at the initial visit were included in the study. RESULTS: Fundus examination revealed posterior staphyloma in only one eye (1.3%) and mild chorioretinal atrophy around the optic disc in 13 eyes (16.3%). There were no patients with choroidal neovascularization or geographic atrophy in the posterior fundus. Myopic peripapillary crescent was observed in 26 eyes (33.8%), but the area of the crescent was relatively small (mean, 0.5 disc area). CONCLUSIONS: The results of the present study showed that myopic fundus changes are uncommon and mild in children. They suggest that aging, in addition to mechanical stretching of the eyeball, might be important for the development of myopic fundus changes.

Atrophy↗
PubMed1979

Myelinated retinal nerve fibers associated with ipsilateral myopia, amblyopia, and strabismus.

Four patients had extensive unilateral myelinated nerve fibers associated with ipsilateral myopia, amblyopia, and strabismus. Their profound visual impairment, exotropia, and the early age onset of symptoms indicated that the amblyopia may have been organically caused. Prognosis is poor for even partial correction but good results have been obtained with intense therapy that includes full correction of the refractive error in each eye and extraocular muscle surgery if cosmetically necessary. In patients with axial myopia, images of a similar size will be produced by placing a lens of the correct power at the spectacle plane. In younger patients, a contact lens should not be used to correct the refractive error because it creates an undesirable anisometropia. Younger patients who have parafoveal fixation and no strabismus respond best to amblyopia therapy.

Adolescent↗
PubMed1982

The mechanism of transient myopia induced by sulfonamide therapy.

We performed acute and convalescent A-scan echographic ocular measurements documenting the anterior chamber depth, lens thickness, and axial length of a patient with acute transient sulfamethoxazole-induced myopia. Shallowing of the anterior chamber, independent of changes in the thickness of the lens, was the only anatomic variation found that could explain the myopia. Swelling of the ciliary body, with forward movement of the lens-iris diaphragm, could produce this transient anatomic change.

Adult↗
PubMedDate not supplied

Myopia--a treatable "disease"?

The authors cite various information and misinformation regarding proposed treatments (atropinization, contact lenses, orthokeratology, wearing glasses, not wearing glasses) for the progression of myopia. They conclude that there is insufficient evidence to support the more vigorous approaches to treatment of myopia, and provide some useful explantations for patients and their parents who question the ophthalmologist's decision to treat conservatively.

Accommodation, Ocular↗
PubMedDate not supplied

Corrective measures for myopia.

Many myopic people, expressing dissatisfaction with traditional methods of optical correction, are interested in a permanent correction of their refractive error which would alleviate dependence on corrective lenses. Although much effort has been put forth in the last century, there is still no method of correcting myopia which is broadly acceptable as safe and effective. The nonsurgical procedures of orthokeratology and the topical use of cycloplegics have not been well proven. Surgical measures are the current vectors of hope. Surgical procedures on parts of the eye other than the cornea have proven to be difficult. Surgery which alters the refractive power of the cornea (refractive keratoplasty) has been used frequently in the past decade. These procedures include keratomileusis, epikeratophakia and radial keratotomy. The latter is currently the most often performed method for the correction of myopia. This paper critiques the major methods, explains their historical development and basic procedures, lists major published studies and discusses their problems and promise for their future.

Contact Lenses↗
PubMed1987

Experimentally induced myopia does not affect post-hatching development of the chick lens.

Myopia, as characterized by a large refractive error (e.g. -10.7 +/- 0.4 D), was induced in post-hatch chicks by a 14 day application of a goggle that was designed to blur the retinal image. In comparison to untreated eyes, the treated eye showed significant changes in wet eye weight and both axial and equatorial lengths. However, the lenses of myopic and non-myopic eyes were not significantly different in focal characteristics, light transmittance or total soluble protein content. Thus the lens neither contributes to, nor compensates for the large refractive error observed in experimentally induced myopia.

Animals↗
PubMed1988

Experimentally induced myopia in chicks: morphometric and biochemical analysis during the first 14 days after hatching.

Application of a translucent goggle over the chick eye on the first day after hatching led to the development of myopia. By the 14th day, the mean refractive error was about -10.0 D. Significant increases in axial and equatorial diameters were observed when the treated eyes were compared with untreated contralateral eyes. The lens did not appear to be affected, either optically or biochemically. A temporal study showed that changes were evident within 2 days of goggle application, and were significantly established 5 days later. Total soluble protein concentrations of the treated and untreated eyes were not significantly different, nor were the dry weights of the sclera and cornea. The enlargement of the eyeball that was observed in the experimental induction of myopia seems due to an increase in fluid within the eye. The data are consistent with the view that refractive properties of the chick eye are dependent upon the clarity of the visual image and modulation of these features occurs after hatching.

Animals↗
PubMed1993

The spatial organization of tyrosine hydroxylase-immunoreactive amacrine cells in the chicken retina and the consequences of myopia.

We examined the spatial organization of the putative dopaminergic amacrine cells in the chicken retina and how this organization was affected by myopic eye enlargement. Myopia was produced by monocular lid suture for 4-7 months from hatching. Dopaminergic amacrine cells (TH-IR) were labelled by tyrosine hydroxylase immunohistochemistry. The somata of the TH-IR cells were usually located at the inner border of the inner nuclear layer; they gave rise to a dense plexus in stratum 1 (S1) of the inner plexiform layer, to a sparse plexus in stratum 3 (S3), and to short spiny dendrites at the border of strata 4 and 5 (S4/S5). The long thin processes in S1 and S3 could seldom be traced to their cell of origin, whereas the S4/S5 dendrites formed discrete fields that tiled the retina with little overlap. Lid suture resulted in retinal expansion of between 25-70%, but the total number of TH-IR amacrine cells was unaltered. Per retina, there were about 4700 TH-IR amacrine cells which showed a 3:1 density gradient from central to peripheral retina. The size of the S4/S5 dendritic fields increased proportionately in the expanded retinae, thus maintaining their coverage across the retina. The increase was achieved through scaled growth of the S4/S5 dendrites, involving both terminal and non-terminal dendrites. These findings suggest that the expansion of retinal neurons during myopia occurred through normal, albeit excessive, growth mechanisms.

Animals↗