Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ASTIGMATISM”

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 847 records · Page 47Linked to original sources
PubMed2006

Comparison of complication rates and postoperative astigmatism between nylon and mersilene sutures for corneal transplants in patients with Fuchs endothelial dystrophy.

PURPOSE: The purpose of this study is to evaluate corneal astigmatism and suture-related complications for transplants sutured with nylon and transplants sutured with Mersilene in primary corneal transplants for Fuchs endothelial dystrophy. METHODS: A retrospective, observational, and comparative study between transplants sutured with either nylon 10-0 or 11-0 (n = 108) or Mersilene 11-0 (n = 58) was done. One hundred sixty-six eyes of 140 patients who received a primary penetrating keratoplasty for Fuchs endothelial dystrophy between 1995 and 2001 at the Rotterdam Eye Hospital in Netherlands were included. RESULTS: Overall, transplant survival did not differ between groups (log-rank test; P = 0.24). During the first 2 years after transplantation, significantly lower astigmatism was seen in transplants sutured with nylon (P = 0.03). Transplants sutured with Mersilene had a significantly higher risk of surgical intervention to correct astigmatism or wound dehiscence after transplantation (hazard ratio, 2.83; 95% confidence interval, 1.34-6.01). Time to first infiltrate, metaplasia (marked scarring along the sutures), or cheesewiring was significantly less in the Mersilene group (P < 0.01). There was a tendency toward a higher risk of complications associated with loose or broken sutures in the nylon group (hazard ratio, 2.00; 95% confidence interval, 0.57-6.98), which was more pronounced after 2 years. CONCLUSIONS: During the first years after corneal transplant surgery, Mersilene sutures are associated with a higher risk of complications and more interventions to correct suture-related problems. However, after 2 years, the grafts seem to be able to retain Mersilene sutures with less risk of suture-related complications as compared with grafts with retained nylon sutures. These favorable long-term effects of Mersilene sutures may outweigh its short-term disadvantage in patients with Fuchs endothelial dystrophy.

Aged↗
PubMed2005

Inefficacy of aspheric soft contact lenses for the correction of low levels of astigmatism.

PURPOSE: The purpose of this article is to compare the visual performance of a toric soft (TS) contact lens (SofLens 66 Toric; Bausch & Lomb, Rochester, NY), an aspheric soft (AS) contact lens (Frequency Aspheric; CooperVision, Fairport, NY) and a spectacle correction (SC) in subjects with low levels of astigmatism. METHODS: One eye of 30 subjects with refractive astigmatism of -0.75 DC or -1.00 DC was tested. After pupil dilation, each subject was fitted with all three forms of correction in random order. Subjects were masked from the contact lens type. High-contrast visual acuity (HCVA) and low-contrast visual acuity (LCVA) were recorded for each correction using 2-mm, 4-mm, and 6-mm artificial pupils. RESULTS: With a 2-mm pupil, HCVA was similar for the TS lens and the SC (p = 0.13); better HCVA was demonstrated with the TS lens than with the AS lens (p = 0.001). With 4-mm and 6-mm pupils, HCVA was poorer with the AS lens than with the SC (p < 0.002) and TS lenses (p < 0.0001). The difference in HCVA between the TS and AS lenses was two letters, three letters, and one line with pupil sizes of 2 mm, 4 mm, and 6 mm, respectively. LCVA was similar for the three refractive conditions with the 2-mm pupil size. With 4-mm and 6-mm pupils, LCVA was similar for the TS lens and SC, but better than the AS lens by approximately one line in each case (all p < 0.0001). CONCLUSIONS: For small pupil sizes, there is little difference in HCVA and LCVA between various refractive corrections. However, for larger pupils, HCVA and LCVA are superior with TS contact lenses and SC versus AS contact lenses by approximately a half-line or more, which is considered to be clinically significant. Superior vision can be achieved for low astigmatic contact lens wearers using TS rather than AS contact lenses.

Adolescent↗
PubMed1994

Refractive keratoplasty for post-graft astigmatism.

Refractive keratoplasty using modified relaxing incisions with compression sutures was performed on 33 patients with high post-keratoplasty astigmatism. The mean reduction in keratometric astigmatism was 8.38 dioptres from a preoperative mean of 12.21 dioptres (SD, 3.59) to 3.93 dioptres (SD, 2.13). All patients noted a marked functional improvement. Two patients required reoperation. One patient required resuturing. Our modification of undercutting the relaxing incisions greatly increases the range of astigmatism that can be treated with this technique.

Astigmatism↗
PubMed1995

Excimer laser surgery for myopia and myopic astigmatism.

Photorefractive keratectomy using the Summit Excimer Laser has been carried out on 1333 eyes with myopia or myopic astigmatism which have been followed up for six months or longer. Of those, 607 have been followed up for one year. Of the eyes with myopia or myopic astigmatism of up to 3 dioptres spherical equivalent, at one year 85.6% had unaided vision of 6/6, 97.2% 6/9 or better, and 99.4% 6/12 or better. Of the eyes between -3.25 and -6.00 dioptres spherical equivalent at one year 72.1% achieved 6/6 vision unaided, 88.8% 6/9 or better, and 94.2% 6/12 or better. Of the eyes between -6.25 and -10.00 dioptres, at one year 49.6% achieved 6/6 vision unaided, 76.1% 6/9 or better and 88.0% 6/12 or better. To achieve these figures, 28% of the patients had astigmatic keratotomy, either two or three weeks before photorefractive keratectomy, or at the same time as photorefractive keratectomy. Photorefractive keratectomy is as predictable as radial keratotomy in eyes of under 6 dioptres myopia, but is more predictable than radial keratotomy in higher myopia. Photorefractive keratectomy has the advantages of leaving an eye which is structurally sound, and without diurnal variation of focusing.

Adult↗
PubMed1984

The astigmatic modulus and its age-dependence.

The question is posed as to why the modulus of the astigmatic vector appears to be randomly distributed with age. This paper investigates astigmatic population distributions. On the assumption of statistical independence, the expected probabilities are determined and compared with the observed values. Measures of central location are examined so as to determine skew distributions. A correlation is sought between the spherical and the astigmatic components of refractive corrections. It is concluded that the modulus is age-dependent but that the variations that occur across the age groups are smaller than can be measured by clinical routines.

Adolescent↗
PubMed1987

A schematic eye model for the effects of translation and rotation of ocular components on peripheral astigmatism.

The relative contributions of translation and rotation of the cornea and lens to peripheral astigmatic asymmetry have been investigated using a linear algebraic ray tracing method. It is believed that lenticular rotation is responsible for angle alpha, so bringing about peripheral astigmatic asymmetry, as normally occurs in human eyes over the temporal and nasal retina. Rotation of the cornea may be responsible for the small numbers of eyes which exhibit large amounts of peripheral astigmatic asymmetry. The effects of corneal rotation and translation on the dimensions of the entrance pupil are illustrated.

Astigmatism↗
PubMed1996

Measurement of astigmatism arising from the internal ocular surfaces.

A method is described for measuring internal ocular surface (posterior cornea, anterior and posterior crystalline lens) astigmatism. This involves the use of videokeratography, A-scan ultrasonography, and autorefractometry along with multi-meridional phakometric measurements of Purkinje images I(anterior corneal surface) II(posterior corneal surface) and IV(posterior lens surface). Data was collected from both eyes of 66 subjects. Right and left eyes exhibited similar mean levels of astigmatism from the posterior corneal surface (R + 0.21 DC axis 82 degrees; L + 0.22 DC axis 80 degrees), anterior lens surface (R + 0.52 DC axis 8 degrees; L + 0.49 DC axis 165 degrees) and posterior lens surface (R + 1.48 DC axis 99 degrees; L + 1.16 DC axis 90 degrees). It was generally found that astigmatism arising from the anterior corneal and lens surfaces in conjunction with intraocular distance effectivity are almost completely compensated for by the posterior corneal and lens surface. Repeatability was assessed on 20 subjects. Although the methods is prone to accumulated experimental errors, these are random in nature so that the difference between repeat group averaged data never exceeded +/- 0.27 DC cylindrical component and +/- 6 degrees cylinder axis.

Adolescent↗
PubMed1994

Correction of astigmatism with Excimer laser transverse keratectomy.

Transverse keratectomies with the Excimer laser were performed on seven eyes of 4 patients with a mean, naturally occurring astigmatism of 5.32D (SD 1.0), range 4.25 to 7.0D. One month later mean astigmatism was 3.46D (SD 1.35), 3 months later 3.8D (SD 1.35), rising to 4.3D (SD 1.6) after 6 months, and to 4.68 (SD 1.4) after 1 year. The refractive cylinder was reduced from a mean of 5.8D to 4.5D and the mean uncorrected visual acuity rose from 0.16 to 0.3. No serious complications occurred, and uncorrected visual acuity could be improved slightly. Excimer laser transverse keratectomy cannot be recommended as a good method to treat high degrees of naturally occurring astigmatism.

Adult↗
PubMed1984

Astigmatism following cataract surgery.

The changes in corneal curvature were determined at regular intervals over a one-year period following intracapsular cataract extraction by microsurgical techniques. During the first postoperative month photokeratometric measurements showed rapid changes in astigmatism associated with large changes in the direction of the axis. Thereafter astigmatism against-the-rule predominated. Data from the small group of patients who underwent surgery in which the technique of phacoemulsification was used show that the smaller changes in corneal curvature are attributable to the smaller incision size and reduced number of sutures. With patients who underwent intracapsular extraction a comparison has been made between the effects of large and small section sizes, and a procedure is outlined whereby surgically induced astigmatism may be minimised.

Aged↗
PubMed1985

Control of postoperative astigmatism.

Thirty-six eyes with excessive astigmatism following cataract extraction via a corneal section were subjected to suture adjustment. This was performed six to eight weeks postoperatively under topical anaesthesia. The cases were selected from a large volume of corneal section cases because they had over 3.0 dioptres astigmatism. We reduced astigmatism significantly in the majority. There were no serious complications.

Aged↗
PubMed1992

A method for assessing the accuracy of surgical technique in the correction of astigmatism.

Surgical results can be assessed as a function of what was aimed for, what was done, and what was achieved. One of the aims of refractive surgery is to reduce astigmatism; the smaller the postoperative astigmatism the better the result. Determination of what was done--that is, the surgical effect, can be calculated from the preoperative and postoperative astigmatism. A simplified formulation is described which facilitates the calculation (magnitude and direction) of this surgical effect. In addition, an expression for surgical accuracy is described, as a function of what was aimed for and what was achieved.

Astigmatism↗
PubMed1979

Residual corneal astigmatism after perforating keratoplasty.

A statistical analysis was made of post-operative astigmatism after perforating keratoplasty in subjects with various corneal diseases. A total of 100 cases were analyzed on discharge (25th day) and 6 months after surgery. The degree of astigmatism and its time course was assessed, and its effect on post-operative visual acuity was investigated, including any changes resulting from removal of the continuous suture. Mean astigmatism values were 4 dioptres on discharge and 4.2 dioptres after 6 months. No statistically significant relation was found between degree of astimatism and recovery of visual acuity.

Adolescent↗
PubMed1981

Myopic astigmatism as a substitute for accommodation in pseudophakia.

Pseudophacic eyes can be made nearly spectacle-independent by increasing the depth of focus of the uncorrected implanted eye. When the postoperative ametropia is a simple myopic astigmatism the uncorrected visual acuity can be above 0.4 from far to near. The quasi-constant visual acuity in different distances is due to the slow change in the dimension of the blurred retinal image when a point source comes nearer to a myopic astigmatic eye. The intersection of Sturm's conoid and the retina (i.e. the blur spot) changes mainly in form but its size changes much less than in a sperical ametropia. To obtain such a refraction the dioptric change in corneal power induced by surgery must be included in the calculation of the intraocular lens. The induced corneal ametropia is a mixed astigmatism with no equivalent power. The optical principles and the clinical results obtained with iridocapsular Binkhorst lenses are discussed.

Accommodation, Ocular↗
PubMedDate not supplied

Photorefractive keratectomy for compound myopic astigmatism with the MEL-70 G-Scan excimer laser.

PURPOSE: To assess the safety, efficacy, predictability and stability of photorefractive keratectomy in compound myopic astigmatism with a moderate and high cylinder component. METHODS: Photorefractive keratectomy was done in 42 eyes with compound myopic astigmatism with the spherocylindrical algorithm of the MEL-70 excimer laser, with wide ablation zones. RESULTS: Spherical equivalent refraction changed from -4.19 +/- 1.65D to -0.05 +/- 0.31D, refractive cylinder from -2.01 +/- 0.71D to -0.09 +/- 0.20D and mean sphere from -3.22 +/- 1.76D to -0.02 +/- 0.26D. Mean uncorrected visual acuity rose from 0.12 +/- 0.17 to 0.91 +/- 0.10. No eye lost lines of spectacle-corrected visual acuity. The safety index was 1.03 and the efficacy index 0.98. Six months from the treatment all eyes were within +/- 1D, 8.9% of eyes were within 0.50D and 44% were plano of target refraction. Refractive and topographical stability were achieved between one and three months after treatment. Transient haze was observed between one and three months after PRK. CONCLUSIONS: Photorefractive keratectomy with the MEL-70 excimer laser to correct myopic astigmatism was a safe and effective procedure with good stability at six months' follow-up. Refractive and visual outcome confirmed that excellent predictability can be expected.

Adult↗
PubMed2003

Modified astigmatism dial diagram for locating eccentric fixation in patients with central scotoma.

PURPOSE: Patients with central scotoma often develop eccentric fixation on a preferred retinal locus (PRL). Identifying the PRL is one of the first steps in low vision rehabilitation training. We present our evaluation of a simple test designed to locate the eccentric fixation in eyes with central scotoma. METHODS: This was a prospective case series of consecutive patients with age-related macular degeneration and bilateral central scotoma. A numeral was added in the center of an astigmatism dial diagram. After one eye was patched, patients with central scotoma were asked to fixate the dial and describe it, then to look at the 12 o'clock position, and then around the clock. The eccentricity at which the central numeral was best seen was compared with the one determined by scanning laser ophthalmoscopy (SLO). The modified astigmatism dial test and SLO were done independently by two masked investigators. The results of the two methods were expressed in clock hour positions and were considered to be in agreement when they did not differ by more than one hour. RESULTS: Nine consecutive patients (18 eyes) with severe age-related macular degeneration and bilateral central scotoma were tested. The six women and three men ranged in age from 61 to 86 years (mean 75.8 years). The pattern test correlated with SLO findings in 12 (66%) of the 18 eyes. When considering the best-seeing eye of each patient, results showed agreement in eight (88%) out of nine cases. CONCLUSIONS: The modified astigmatism dial test appears useful for establishing the location of the eccentric fixation in the best-seeing eye of patients with bilateral central scotoma, allowing visual rehabilitation training to be started without delay.

Aged↗
PubMed1989

Surgical correction of astigmatism using paired T-incisions.

Transverse incision astigmatic keratotomy procedures were performed, combined with radial keratotomy, in 16 eyes for correction of astigmatism and coexisting myopia. We used a transverse incision technique in which T-incisions vertically intersected radial incisions of the steepest corneal meridian. After a mean follow-up period of 10 months with a range of six to 27 months, an average 1.92 diopters of the cylinder was corrected. In comparison with 2.11 diopters of the cylinder corrected at postoperative one day, there was a 22.8% decrease in the effect of astigmatism correction after a postoperative period averaging 10 months.

Adolescent↗
PubMed2004

The efficacy of multi-zone cross-cylinder method for astigmatism correction.

The purpose of this study is to assess the efficacy of the multi-zone cross-cylinder method as compared with the single method for astigmatism correction using LASIK. This prospective study enrolled 40 patients (52 eyes) who underwent the cross-cylinder method using LASIK, and 52 patients (60 eyes) who underwent the single method using LASIK: all patients were given a diagnosis of complex myopic astigmatism from the department of ophthalmology of this hospital between January 2002 and July 2003. Preoperatively, the mean spherical equivalent refraction was -3.85 +/- 1.13 D in the cross-cylinder group and -4.05 +/- 1.20 D in the single method group (p = 0.23). The mean cylinder was -2.05 +/- 1.58 D in the cross-cylinder group and -1.95 +/- 1.12 D in the single method group (p = 0.31). 6 months after treatment the results were a mean spherical equivalent refraction of -0.26 +/- 0.30 D in the cross-cylinder group and -0.34 +/- 0.35 D in the single method group (p = 0.13). The mean cylinder was -0.38 +/- 0.29 D in the cross-cylinder group and -0.45 +/- 0.30 D in the single method group (p = 0.096). There were no statistically significant differences between the two groups. The mean BCVA was not different from mean preoperative BCVA in both groups (i.e., 0.98 +/- 0.10, 0.96 +/- 0.25, p = 0.86). Postoperatively, patient complications that included night halo, glare and corneal haze were not noted in either group. In conclusion, the results of cross-cylinder method are no different from the single method for the correction of a complex astigmatism. In the future, studies will have to be conducted to assess the efficacy of the cross-cylinder method in consideration of those factors that can affect the postoperative outcome.

Adult↗
PubMedDate not supplied

The effect of oblique muscle surgery on the axis of astigmatism.

A series of 22 highly astigmatic eyes in 14 patients underwent surgery, either in the form of recessing the inferior oblique, tenotomizing the superior oblique, or tightening the superior oblique. The refractive errors obtained in a masked manner six months postoperative were compared to those preoperative. Weakening the inferior oblique or tightening the superior oblique produced a long-term incyclorotation (clockwise for right eyes and counterclockwise for left eyes) of the axis of astigmatism of approximately 10 degrees. Tenotomizing the superior oblique produced a long-term excyclorotation (counterclockwise for right eyes and clockwise for left eyes) of the axis of astigmatism of about 10 degrees.

Astigmatism↗