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At least 19 recordsLinked to original sources

PubMed2026

Astigmatic vector outcomes after FS-LASIK versus SMILE for high myopic astigmatism: a single-center retrospective comparative cohort study without cyclotorsion compensation.

PURPOSE: To compare astigmatic correction vector outcomes between femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and small-incision lenticule extraction (SMILE, also termed Keratorefractive Lenticule Extraction, KLEx) without intraoperative cyclotorsion compensation in patients with high myopic astigmatism (- 2.00 to - 3.75 D), and to clarify procedure-specific correction tendencies under this non-standardized alignment protocol. METHODS: This single-center retrospective comparative cohort study enrolled 155 eyes (one eye randomly selected per patient) that underwent FS-LASIK (80 eyes) or SMILE/KLEx (75 eyes) for high myopic astigmatism correction from January 2023 to July 2024 in Beijing Fenglian Jiayue Lige Clinic. Intraoperative cyclotorsion compensation was intentionally disabled to isolate inherent procedural astigmatism correction characteristics. Standardized Alpins vectorial analysis was performed at 3 months and 12 months postoperatively. PRIMARY ENDPOINT: 12-month Alpins correction index (CI). Multivariable propensity score adjustment was applied to mitigate confounding by clinical treatment selection bias. Statistical multiplicity control was implemented for secondary vector and visual outcomes. RESULTS: Baseline demographic, refractive, corneal and ocular biometric parameters were balanced between groups after propensity matching. No statistically significant intergroup differences were detected in uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), residual cylinder, safety index or efficacy index at 3 and 12 months (all P > 0.05). Under the non-cyclotorsion-compensated protocol, significant intergroup differences were identified in the magnitude of surgically induced astigmatism (SIA), correction index (CI), and magnitude error (ME) at both follow-up timepoints (all P < 0.0001). Target induced astigmatism (TIA), difference vector (DV), index of success (IOS), and angle error (AE) magnitudes were comparable between groups (all P > 0.05). The vector mean axis of DV differed significantly between groups at 3 and 12 months (Watson-Williams circular test, all P < 0.0001). No reoperations were documented in clinic medical records for either cohort. No standardized dry eye questionnaires, tear film testing or corneal nerve density metrics were collected to quantify dry eye adverse events; only unstructured clinical notes were reviewed for complication screening. CONCLUSIONS: Under surgical alignment without cyclotorsion compensation, FS-LASIK and SMILE/KLEx both yielded acceptable visual and refractive safety/efficacy for high myopic astigmatism (- 2.00 to - 3.75 D) at 1-year follow-up, but demonstrated divergent astigmatism correction tendencies: FS-LASIK exhibited relative astigmatism overcorrection (vector mean DV: - 0.35 ± 0.43 D × 91°, CI > 1), while SMILE/KLEx showed relative undercorrection (vector mean DV: - 0.21 ± 0.53 D × 12°, CI < 1). These correction biases are specific to the study's manual limbal alignment protocol without cyclotorsion tracking and cannot be generalized to modern optimized surgical platforms equipped with automated cyclotorsion compensation. Residual refractive errors across both groups are likely multifactorial, including differential corneal stromal healing responses, divergent femtosecond/excimer laser tissue modification mechanisms, and uncorrected intraoperative ocular cyclotorsion.

Humans↗

PubMed1992

Similarities and differences between the Kelman phacoemulsification and extracapsular cataract extraction procedures in the spontaneous regression of corneal astigmatism from against-the-rule astigmatism.

We perspectively examined the induction and spontaneous regression of corneal astigmatism from preoperative against-the-rule astigmatism [Kelman phacoemulsification (KPE), n = 618; extracapsular cataract extraction (ECCE), n = 192] among cataract extraction surgeries (KPE, n = 1,648; ECCE, n = 443). All data were set on a double-angle coordinate graph, from which the mean +/- SE of the axis and the amount of astigmatism were obtained simultaneously. In the KPE group, the surgically induced astigmatism was independent of preoperative state or age. In the ECCE group, surgically induced astigmatism shifted toward with-the-rule astigmatism, and postoperative recovery was delayed longer in patients over 80 years of age than in those under 70. Postoperative against-the-rule astigmatism was more frequent after KPE. Our first trial to calculate astigmatism from a double-angle coordinate graph was useful in showing astigmatism changes.

Aged↗

PubMed1977

[Corneal and total astigmatism. Report II: Studies on cases with total astigmatism (author's transl)].

Explore the source record for details and available documents.

Adolescent↗

PubMed1992

Postcataract against-the-rule astigmatism after phacoemulsification procedure. Characteristic changes over time.

To further determine whether postoperative astigmatism is related to the amount of preoperative astigmatism, we analyzed two types of against-the-rule (AR) astigmatism induced by phacoemulsification and aspiration (PEA) procedures. The operations all utilized 10-0 polyester (Mersilene) in double running fashion for the closure of the corneoscleral incisions. The induction and spontaneous regression of several types of astigmatism were analyzed over 6 months. Surgery was all done by one surgeon, with the same surgical procedure and the same number of sutures. In postoperative AR astigmatism less than 0.7 D at 6 months, although the amount of the astigmatism 1 week postoperatively was remarkably increased (2.66 +/- 0.17 D), postoperative astigmatism was decreased 6 months following surgery. On the other hand, in postoperative AR astigmatism greater than 1.5 D at 6 months, the power of the astigmatism 1 week postoperatively (2.12 +/- 0.13 D) was not much higher than the preoperative level (1.38 +/- 0.08 D), but tended to continue increasing even 6 months after surgery. There was no difference in the power of astigmatism between 1 and 3 months postoperatively. The eyes with preoperative astigmatism (e.g. 1.38 +/- 0.08 D) and especially preoperative AR astigmatism (e.g. 1.60 +/- 0.11 D), showed an increase of their astigmatism after the PEA procedure. We discussed some risk factors which may induce greater postoperative AR astigmatism.

Astigmatism↗

PubMed1992

Outcome of preoperative against-the-rule astigmatism after phacoemulsification: characteristic changes over time. Part II.

To determine the outcome of preoperative against-the rule (AR) astigmatism among 1,648 phacoemulsification and aspiration (PEA) procedures, we analyzed the post-cataract time course of astigmatism over 6 months in 618 eyes divided into three groups. In preoperative AR astigmatism less than 0.75 dptr (n = 208), the astigmatism increase 1 week postoperatively was rapid. In preoperative AR astigmatism greater than or equal to 1.5 dptr (n = 185), no difference in the power of astigmatism was apparent between 1 and 3 months postoperatively. The third group (0.75 less than or equal to preoperative AR astigmatism less than 1.5 dptr, n = 143) showed intermediate characteristics. The eyes with preoperative low AR astigmatism showed exacerbation of astigmatism after the PEA procedure, whereas the degree of astigmatism, corneal curvatures and the rate of AR astigmatism became lower in the eyes with higher preoperative AR astigmatism.

Aged↗

PubMed1977

Astigmatism in cataract surgery.

We report on our investigation into astigmatism in 40 eyes following a corneal cataract incision closed with a continuous 10/0 nylon monofilament suture (Ethilon). Immediately after surgery there was astigmatism caused by the nylon suture (suture-induced astigmatism), its severity depending on the tightness of the suture. It ranged from 1 to 10-5 dioptres, the mean value 4-09 dioptres with a standard deviation of +/-2-5. Removing the nylon suture eliminated this astigmatism and within a few weeks the corneal astigmatism correction in 48% of eyes returned to the preoperative level. In 80% of eyes the difference between the final postoperative corneal astigmatism (4 months after removing the continuous suture) and the preoperative astigmatism was 0-75 dioptres or less and the maximum change was 1-5 dioptres. In 40% of eyes the axis of the cylinder changed from a horizontal to an oblique axis but did not change from a with- to against-the-rule axis. The degree of astigmatism remained constant while the suture was in place and in 50% of eyes was equal to or less than 3 dioptres. The mean of the spherical equivalents was 11-31 dioptres with a standard deviation of +/-1-25. A spectacle correction 14 days after operation prescribed either as the mean spherical equivalent (11-50 dioptres) or according to the patient's refraction will give satisfactory vision until the suture is removed 4 months after operation. The degree of astigmatism following a corneal section and continuous nylon suture compares very favourably with astigmatism following other suturing techniques for cataract.

Astigmatism↗

PubMedDate not supplied

Selective suture cutting for control of astigmatism following cataract surgery.

Use of 10-0 monofilament nylon in ECCE cataract surgery leads to high with the rule astigmatism. Many intraoperative and post operative methods have been used to minimise post operative astigmatism. We did selective suture cutting in 38 consecutive patients. Mean keratometric astigmatism at three and six weeks post operative was 5.76 and 5.42 dioptres (D) respectively. 77.5% of eyes had astigmatism above 2 D. Selective suture cutting along the axis of the plus high cylinder was done after six weeks of surgery. Mean post suture cutting keratometric astigmatism was 3.3 D and 70% of the eyes had astigmatism below 2 D. After 3 months of surgery mean keratometric astigmatism was reduced to 1.84 D. Axis of the astigmatism also changed following suture cutting. 40% of the eyes showed improvement in their Snellen acuity following reduction in the cylindrical power.

Adult↗

PubMedDate not supplied

Combined transverse and interrupted radial keratotomy for compound myopic astigmatism.

BACKGROUND: A variety of patterns of keratotomy are used to correct naturally occurring astigmatism. We evaluated straight transverse incisions with interrupted radial incisions (jump radials). METHODS: In 32 human eyes with naturally occurring astigmatism, we used straight transverse incisions with interrupted radial incisions, with or without additional radial keratotomy, to correct compound myopic astigmatism. The range of preoperative refractive astigmatism was 1.00 to 3.50 D. RESULTS: The mean follow-up time was 15 months (range, 12 to 18 months). The average surgically corrected astigmatism was 1.55 +/- 0.29 D. Eighty-seven percent of the eyes achieved less than 1.00 D of astigmatism, and the remaining four eyes retained 1.00 to 1.25 D of astigmatism. CONCLUSION: Combined transverse and interrupted radial incisions are effective in correcting naturally occurring astigmatism.

Adult↗

PubMed1979

An analysis of corneal transplantation: II--postoperative astigmatism.

An analysis of 153 penetrating keratoplasties was undertaken. The same surgical technique was used in all cases. Three factors had a statistically significant effect on postoperative astigmatism, as measured by keratometry. (1) Astigmatism decreased with increasing follow-up time (P less than 0.05). (2) Vitreous loss at the time of the keratoplasty increased the amount of postoperative astigmatism (P less than 0.05). (3) Females had more postoperative astigmatism than males (P less than 0.05), but this was probably related to a tendency for females to have a greater incidence of postoperative anterior synechiae (P just greater than 0.05), and the fact that all 6 cases of vitreous loss were in females. There was an almost significant trend toward postoperative anterior synechiae being associated with increased astigmatism (P just greater than 0.05), and there was also a trend toward the division of these synechiae reducing the amount of astigmatism. Fifteen of the 153 penetrating grafts were done in cases of herpes simplex. These were compared with 11 lamellar grafts done for herpes simplex, and there was a statistically insignificant trend toward more postoperative astigmatism in penetrating grafts.

Astigmatism↗

PubMed1992

Induced astigmatism following small incision cataract surgery combined with trabeculectomy.

The combination of phacoemulsification and implantation of foldable intraocular lenses through a small incision with a trabeculectomy is increasingly preferred in glaucoma patients with coexisting cataract. Small incisions induce less astigmatism and thereby enhance visual recovery. This study should clarify if this benefit of small incision cataract surgery is preserved when combined with a trabeculectomy. Thirty-five eyes were included in this study. Preoperative astigmatism measurements were compared with those obtained one month and one year postoperatively. Vector analysis was performed. A series of 30 cases which underwent small incision cataract surgery alone were used as a control group. One month postoperatively the eyes undergoing the combined procedure showed about the same with-the-rule astigmatic peak (mean: +0.32 dpt.) as the control group eyes (mean: +0.26 dpt.; p > 0.05). One year postoperatively both groups showed the same against-the-rule astigmatic shift (mean: -0.28 dpt.; p > 0.05). In conclusion, patients undergoing small incision cataract surgery combined with trabeculectomy showed a small amount of surgically induced astigmatism. When compared with patients which underwent small incision cataract surgery alone, the difference in astigmatic changes was found to be statistically not significant.

Astigmatism↗

PubMed1979

Corneal astigmatism after cataract extraction. A comparison of corneal and corneoscleral incisions.

Corneal astigmatism after cataract surgery by way of corneal incision (C, n = 62) and corneo-scleral incision (CS, n = 61) was followed for six months. Corneal incisions were closed by continuous nylon 10--0 (7--25 loops, median 14). Corneo-scleral incisions were sutured with single knots (2--10, median value 5). Keratometric results in the C and CS groups are compared. Concerning the degree of astigmatism, pre-operative median values were 0.5 and 0.7 D, respectively. After one week they were 4.5 and 3.0 D; after two weeks 3.3 and 3.0 D; after four months 3.0 and 2.0 D; after six months (final status) 1.5 and 1.7 D, respectively. The differences between C and CS were not significant. For both, astigmatism after cataract surgery did not quite return to pre-operative levels. Concerning the axis (weaker meridian) of corneal astigmatism, the C cases retained their pre-operative distribution, while the CS cases showed the classical shift towards against-rule astigmatism. Final corrected visual acuity was of the same order in the C and CS group. Due to frequent shifts, also of the axis, it is recommended by early (preliminary) glass prescription not to correct the astigmatism, but to give only the best spherical correction.

Adult↗

PubMed1976

What causes astigmatism?

Although spectacles were invented in the 13th century, methods of testing for astigmatism have been developed only within the past one hundred years. Even today, the etiological factors responsible for corneal astigmatism are not well understood. A mechanism which may account for the existence of corneal astigmatism is proposed, on the basis of data concerning changes in astigmatism with age, racial variations in astigmatism and changes in astigmatism due to the wearing of contact lenses.

Adolescent↗

PubMed1979

Astigmatic considerations in corneal graft.

Some fictions about astigmatism should be dispelled: 1) Sutures determine astigmatism. They do not. 2) The size of the graft is contributory to astigmatism. It is not contributory. 3) Anterior or posterior cutting of the graft makes no difference. It does make a difference. 4) Same size trephine can be used to cut graft and recipient opening. Not when graft is cut from posterior surface or significant flattening will result. 5) A small cutting error is of no consequence. A small cutting error can cause a great deal of astigmatism. Tissue factors are paramount. Sutures must maintain wound apposition primarily. Posterior cutting requires a larger diameter trephine. A one-half-mm cutting error can cause an astigmatism of five diopters. Excessive corneal astigmatism, when it does occur, can be controlled by corneal wedge resection. The surgical keratometer identifies and limits surgical and suture-induced errors. Success in microsurgical keratoplasty can no longer be defined only as a clear graft. It must include also minimal or no residual optical error.

Astigmatism↗

PubMed1978

Resolution acuity in astigmats: evidence for a critical period in the human visual system.

Astigmats, who have been fully optically corrected, show an acuity configuration highly characteristic of the uncorrected astigmatism when they are tested with gratings of different orientations. This phenomenon, which is called meridional amblyopia, has been supposed to be neural in origin. This paper attempts to show that there is evidence for a critical period in the visual system of humans. In the experiment described here twelve astigmatic subjects were tested against a control group of six non-astigmatic (emmetropic) subjects. The astigmatic subjects differed in the ages at which they had been initially optically corrected. Square-wave gratings were used to test the subjects and measures of acuity for different orientations were recorded. It was found that those astigmatic subjects corrected above the age of seven showed the usual acuity decrement while those corrected below seven showed significantly smaller meridional amblyopia. The age of seven, therefore, was taken to mark the end of a critical period in the development of the human visual system, after which the system ceases to be structurally influenced by visual input.

Adult↗

PubMed1992

Comparison between postoperative astigmatism after classic extracapsular lens extraction and after phacoemulsification with implantation of a Pearce tripod or Pearce vaulted Y-loop intraocular lens.

We compared the surgically induced astigmatism after standard extracapsular cataract extraction (ECCE) with the astigmatism following cataract extraction by phacoemulsification. The surgically induced corneal astigmatism was assessed on several occasions, ranging from one day to one year postoperatively. After phacoemulsification, this astigmatism was considerably slighter than after ECCE on day 1 postoperatively and after two and six weeks. However, one year postoperatively, this difference was less clear. We then measured slight against-the-rule astigmatism for both surgical techniques.

Astigmatism↗

PubMed1978

Residual astigmatism in hard and soft contact lens wearers.

Residual astigmatism in a group of hard contact lens wearers and an equal size group of soft contact lens wearers was compared. Generally, the criteria used were to fit patients with refractive astigmatism greater than 0.75 D with hard lenses and those with refractive astigmatism of 0.25 D or less with soft ones. Those with refractive astigmatism between 0.25 D and 0.75 D were fitted with either modality depending upon other factors. The amount of residual astigmatism in the two groups proved to be nearly equal.

Astigmatism↗

PubMed1976

[Corneal astigmatism after penetrating keratoplasty with direct and indirect sutures (author's transl)].

After a full thickness optic keratoplasty the corneal astigmatism of 116 eyes was checked. 72 cases had been operated on with indirect, 44 with direct sutures. Up to the sixth month after the operation the astigmatism was found to be equally distributed between 0.75 and 12 dpt and until the end of the second year between 0.75 and 8 dpt. Neither the way of suturing nor the diameter of the graft nor the kind of corneal lesion had any influence on the postoperative astigmatism. After six months, the height and the axis of the astigmatism remained approximately constant; however, in four cases of keratokonus followed up for nineteen years the astigmatism gradually increased.

Astigmatism↗

PubMed1977

Astigmatism of the mammalian cornea: evolutionary and perceptive significance.

Astigmatism enables spatial, linear and directional discrimination. These faculties are demonstrated by astigmatic photographic experiments. Comparative anatomic deductions lead to the assumption that the eyes of early mammals were astigmatic. Thereby these animals, lacking binocularity and accommodation, could achieve visual spatial information. This assumption is supported by the fact that features of astigmatic refraction, specially straight linearity, have been adopted by various intra-ocular structures, and by the neuronal structuralisation of receptive fields in the visual cortex of mammals.

Animals↗