Astigmatic neutrality in biaxial microincision cataract surgery

Retrospective analysis of cataract surgery outcomes in China from 2009 to 2018: from a national registry system data

OBJECTIVE

To evaluate patients' benefits after cataract surgery and to form recommendations for Chinese national health policy decision makers and administration departments based on the quality of cataract treatments.

METHOD

An observational study based on real-world data source from the National Cataract Recovery Surgery Information Registration and Reporting System.

RESULTS

A total of 14 157 463 original records were reported from 1 July 2009 to 31 December 2018. The factors that influenced the 3-day postsurgical best-corrected visual acuity (BCVA), the primary outcome, were analysed by logistic regression analysis. We found that a history of hypertension (OR=0.916) or diabetes (OR=0.912), presurgical pupil abnormality (OR=0.571) and high intraocular pressure (OR=0.578) were harmful to the postsurgical BCVA improvement (BCVA ≥6/20), while male sex (OR=1.113), better presurgical BCVA level (OR=5.996 for ≥6/12-<6/7.5 and OR=2.610 for >6/60-<6/12 taken ≤6/60 as reference), age-related cataract (OR=1.825) and intraocular lens implantation (OR=1.886) were statistically beneficial to the postsurgical BCVA improvement. Compared with extracapsular cataract extraction (ECCE) with large incision, the ECCE with small incision (OR value=1.810) and the phacoemulsification (OR=1.420) significantly improved the benefit probability.

CONCLUSION

ECCE with small incision has comparable effects on postsurgical BCVA improvement of phacoemulsification. Therefore, ECCE could be an alternative cataract surgical treatment in economically underdeveloped areas in China, provided the surgeons are adequately trained.

Toric intraocular lenses: Evidence‐based use

Uncorrected refractive astigmatism degrades visual acuity. Spherical intraocular lenses (IOLs) leave astigmatic errors resident in the cornea manifest in refractive astigmatism. Toric IOLs, correcting for this corneal astigmatism, contribute to spectacle‐free vision in the pseudophakic eye. This review provides information to assist surgeons in a rational choice of eyes suitable for toric IOL implantation, methods of IOL cylinder power calculation, surgical techniques for toric IOLs and management of complications. With appropriate application of this information, correction of visually detrimental astigmatism can be achieved routinely.

Optical quality and visual performance after cataract surgery with biaxial microincision intraocular lens implantation

PURPOSE

To evaluate the time course of the optical quality and visual performance with a microincision monofocal intraocular lens (Incise).

SETTING

Hospital Torrecárdenas, Almería, Spain.

DESIGN

Prospective study.

METHODS

The visual and refractive outcomes were evaluated in eyes with the microincision IOL preoperatively and 1, 3, and 6 months postoperatively. The modulation transfer function (MTF) cutoff frequency, Strehl ratio, and objective scatter index (OSI) were used to measure optical quality. The contrast sensitivity function (CSF) and the visual disturbance index characterized visual performance.

RESULTS

In the 32 study eyes, the mean values preoperatively and 6 months postoperatively, respectively, were MTF cutoff frequency (11.40 cycles per degree [cpd] ± 8.39 [SD] and 23.33 ± 11.68 cpd; P < .001), Strehl ratio (0.078 ± 0.32 and 0.15 ± 0.07; P < .05), and OSI (7.44 ± 3.25 and 1.57 ± 0.26; P < .001). At each spatial frequency, the CSF significantly differed between preoperatively and postoperatively (P < .001). The mean visual disturbance index changed from 0.70 ± 0.28 to 0.31 ± 0.17 (P < .001). For all parameters studied, statistically significant differences were found between the preoperative and postoperatively values, with no differences between the results 1, 3, and 6 months after surgery (P > .05).

CONCLUSIONS

Biaxial microincision cataract surgery provided optimum clinical outcomes. The optical quality and visual performance improved significantly 1 month after surgery, with the results remaining stable at 6 months. The postoperative visual function was similar to that in subjects of the same age with healthy eyes.

FINANCIAL DISCLOSURE

None of the authors has a financial or proprietary interest in any material or method mentioned.

Outcome of adjustment for posterior corneal curvature in toric intraocular lens calculation and selection

PURPOSE

To evaluate the accuracy of the cylinder power choice and the astigmatic refractive outcome for toric intraocular lenses (IOLs), the cylinder power of which was calculated using the Goggin nomogram that allows for the likely effect of posterior corneal astigmatism.

SETTING

The Queen Elizabeth Hospital, Adelaide, Australia.

DESIGN

Observational case series.

METHODS

The absolute value of the prediction error of the toric IOL cylinder power effect in consecutive eyes with preoperative anterior keratometric cylinder values of 1.0 diopter (D) or more was compared with the absolute value of the prediction error in a historical control group. The anteriorly measured keratometric cylinder values were altered by 2 coefficients of adjustment, one for with-the-rule eyes and one for against-the-rule eyes, before calculation of the IOL cylinder power to be implanted. In the controls, unadjusted keratometric cylinder values were used.

RESULTS

The case-series group comprised 31 eyes (29 patients) and the control group, 65 eyes. The absolute error in prediction of the toric IOL cylinder power effect was reduced from a median of 0.45 D (95% confidence interval [CI], 0.33-0.58) in the controls to a median of 0.23 D (95% CI, 0.13-0.35) in the adjusted eyes (P = .004).

CONCLUSION

Adjustment of toric IOL cylinder power by application of a coefficient of adjustment to anteriorly measured keratometric cylinder values based on the keratometric rule of the eye led to a clinically and statistically significant improvement in refractive astigmatic outcome.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Vector analysis investigation of toric intraocular lens with no deviation from the intended axis

AIM

The aim of this research was to evaluate vector analysis after implantation of toric intraocular lenses (IOLs) without deviation from the intended axis.

METHODS

The study included 18 eyes of 16 patients who underwent cataract surgery with the insertion of a toric implant (AcrySof IQ Toric). The postoperative IOL meridian placement completely corresponded to that planned. Using vector analysis, surgically induced astigmatism (SIA) was derived from the refractive outcome versus the predicted postoperative keratometric astigmatism and was compared with targeted induced astigmatism (TIA). The difference vector (DV) was derived by calculating the vector expression of the remaining astigmatic change.

RESULTS

The mean postoperative remaining refractive astigmatism of 0.73±0.55 diopters (D) was achieved versus the mean target of 0.44±0.28 D. There was a difference of 0.29 D between the target and achieved values. The mean SIA value was 1.90±0.99 D compared with the mean TIA value of 2.00±0.85 D. The mean DV value was 0.87±0.56 D. The astigmatism correction index (SIA/TIA) was 0.95, which was near the ideal value of 1. The index of success (DV/TIA) was 0.44, which was far from the ideal value of 0.

CONCLUSION

The implantation of toric IOLs is an effective, predictable method for astigmatic correction. However, some remaining astigmatism is present even if toric IOLs are placed accurately.

Value of posterior keratometry in the assessment of surgically induced astigmatic change in cataract surgery

PURPOSE

To investigate the value of posterior keratometry in the assessment of surgically induced astigmatic change (AC) in cataract surgery, with particular emphasis on the influence of test-retest variability.

METHODS

Seventy-seven eyes of 77 cataract patients scheduled for routine cataract surgery were enrolled. All patients received a 2.2-mm self-sealing scleral incision (n = 24), single-plane clear corneal incision (SPCCI; n = 29) or biplanar clear corneal incision (BPCCI; n = 24). Measurements of anterior and posterior corneal astigmatism were performed with a rotating Scheimpflug camera (Pentacam HR) preoperatively and postoperatively. Two repeated readings were taken preoperatively to assess the role of the test-retest effect. Astigmatic change (AC) was analysed according to the polar value method.

RESULTS

On the anterior corneal surface, SPCCIs and BPCCIs caused a statistically significant mean flattening of the incisional meridian of 0.37 and 0.27 dioptres (D), respectively. Scleral incisions on average did not cause AC, although steepening, flattening or torque beyond the test-retest effect was observed in individual cases. On the posterior surface, mean power changes in the incisional meridian were below 0.1 D for all incisions, and these changes were of the same order of magnitude as the test-retest effect.

CONCLUSION

Surgically induced AC of the posterior corneal surface after cataract surgery is of negligible clinical relevance. Moreover, it is of the same order of magnitude as the test-retest variability of the measurement device and therefore cannot (yet) be reliably assessed.

The role of sideport incision in astigmatism change after cataract surgery

PURPOSE

To study the changes in corneal astigmatism after cataract surgery when the sideport incision is performed at a predetermined location away from the tunnel incision.

SETTING

General Hospital of Piraeus "Tzaneio", Attiki, Greece.

MATERIALS AND METHODS

A total of 333 eyes with corneal astigmatism ≤1.5 diopters (D) underwent cataract surgery. A three-step superotemporal clear corneal incision for the right eye and a superonasal clear corneal incision for the left eye (3.0 mm) was made, while the sideport incision was located at <90°, 90°-110°, and >110°. Keratometric data were measured with corneal topography EyeSys Vista 2000 pre- and postoperatively at the 1st and 6th month. Surgically induced astigmatism was calculated by vector analysis. We noted all cases in which a change >0.5 D in corneal astigmatic power occurred, as well as a change >20° in axis torque, despite axis direction.

RESULTS

After multiple logistic regression analysis was conducted, cases with >110° distance between the tunnel and sideport incision had 2.22 times (P=0.021) greater likelihood for having changed >0.5 D in astigmatic power at the 1st month and 3.45 times (P=0.031) at the 6th month postoperatively, as compared with cases with a 90°-110° distance between the tunnel and sideport incision. As for the change in the astigmatic axis, cases with <90° distance had a 4.18 times greater likelihood for having a change >20° (P<0.001) (preoperative to 1st month) as compared with cases having 90°-110° of distance.

CONCLUSION

For surgeons that operate only from the superior position, we propose that in order to produce an incision that is as "astigmatically neutral" as possible, they should perform the sideport incision at a 90°-110° distance.

Comparison of corneal aberrations after biaxial microincision and microcoaxial cataract surgeries: a prospective study

PURPOSE

To compare the effects of biaxial microincision cataract surgery (B-MICS) and microcoaxial cataract surgery (C-MICS) techniques on corneal optical quality.

MATERIALS AND METHODS

In this prospective study, 40 eyes underwent B-MICS and 40 eyes C-MICS. Corneal aberrations were derived from conversion of the corneal elevation profile into corneal wavefront data with 6.0  mm aperture diameter using Zernike polynomials by corneal topography preoperatively and 1 month postoperatively. Both magnitude and axes of surgically induced corneal aberrations were calculated.

RESULTS

Mean final incision widths were 1.80 ± 0.09  mm and 1.89 ± 0.11  mm (p = 0.062) in B-MICS and C-MICS groups, respectively. There were no significant changes in total and higher order root mean square in both groups postoperatively. In B-MICS group, all aberration terms were similar, before and after surgery. However, vertical coma (p = 0.002), vertical trefoil (p < 0.001) and primary trefoil (p = 0.042) significantly increased postoperatively in the C-MICS group. Except surgically induced trefoil (p = 0.047), there was no significant difference in all surgically induced corneal aberrations between groups. The axes of the induced trefoil were found to be mostly related and close to the incision site in both groups which was more prominent in the C-MICS group.

CONCLUSIONS

Microincision cataract surgery techniques performed through sub-1.9  mm clear corneal incisions do not generally degrade optical quality of the cornea while only small amount of higher order aberrations seem to be induced with C-MICS technique.

Development of biomedical publications on ametropia research in PubMed from 1845 to 2010: a bibliometric analysis

AIM

We have carried out a bibliometric analysis on the development of ametropia literature to determine its growth rule and tendency, and to provide the basis for the problems related to ametropia research.

METHODS

Literatures that contained the descriptors of ametropia in title or paper published before Nov. 10, 2010 in PubMed databases (www.ncbi.nlm.nih.gov/Pubmed) were selected. As bibliometric indicators of ametropia, biomedical journals referring to ophthalmology by ISSN were calculated. The principal bibliometric indicators: Price's and Bradford's laws were applied on the increase or dispersion of scientific literature, the participation index of languages and the journals. By means of manual coding, literatures were classified according to documents study and statistical analysis.

RESULTS

The literatures cited in ametropia, astigmatism, myopia and hypermetropia had accumulated to 26475, which consists of Review (n=1560), Randomized Controlled Trial (n=776), Practice Guideline (n=10), Meta-Analysis (n=23), Letter (n=1222), Editorial (n=328), Clinical Trial (n=1726) and Others (n=20830), and Humans (n=23073), Animals(n=1434) and others (n=1968). 1136 literatures were included in PubMed Central, 22384 in MEDLINE and 2955 in others. The ametropia literatures rose every 5 years which of the ametropia-year cumulated amount of the literatures had three periods: before 1900, slowly increasing from 1901 to 1950, rapidly rising from 1951 to 2010 (increased approximate exponentiation exponent). Sixty kinds of languages listed in PubMed databases, of which English is dominant for aborting to ametropia research documents before 2010 (77.32%, 20471/26475). The document languages of top eight account for 95.58% (English, German, French, Japanese, Russian, Italian, Spanish, Chinese), and others for 4.42% (1171/26475). The SCI database includes 48 ophthalmologic journals and the impact factor of 39 journals is ≥1 on Thomson-Reuters in 2010. Of 48 ophthalmologic journals, there were 14785 documents (55.85%) of ametropia, astigmatism, myopia, and hypermetropia. Others were without exception.

CONCLUSION

The bibliometric analysis results show that ametropia literature are increased progressively, approximate exponentiation exponent during 1951-2010. In addition, ametropia research has become more popular since nearly half century.