Comparative study of objective visual quality between FS-LASIK and SMART in myopia.

AIM: To compare the changes in the objective visual quality of patients with low and moderate myopia postoperatively after transepithelial photorefractive keratectomy using the smart pulse technology (SMART) and femtosecond laser in situ keratomileusis (FS-LASIK). METHODS: Corneal higher-order aberrations (HOAs), horizontal coma, vertical coma and spherical aberration were measured using Pentacam, and cutoff for modulation transfer function (MTF cutoff), objective scatter index (OSI) and Strehl ratio (SR) was measured using an optical quality analysis system (OQAS-II), before and after operation at 1, 3, and 6mo, and data were analyzed by repeated measurement two-way analysis of variance. RESULTS: The difference in uncorrected distance visual acuity between SMART and FS-LASIK was statistically significant only 1wk postoperatively. Approximately 86.36% and 80.69% of patients with spherical equivalent (SE) in ±0.50 D were observed in the SMART and FS-LASIK groups, respectively. No significant difference was observed in SE between the two groups (P=0.509). The HOAs increased postoperatively compared with those before surgery in both groups (P<0.05). No significant difference in HOA, corneal horizontal coma, spherical aberration, ΔHOA, Δhorizontal coma, and Δspherical aberration were observed between the two group (P>0.05). Corneal vertical coma and Δcorneal vertical coma in the FS-LASIK group were higher than those in the SMART group (P<0.05). The OSI of both groups at 1mo after surgery was higher than that before surgery (P<0.05). At 3 and 6mo postoperatively, the OSI in the FS-LASIK group was slightly higher than that in the SMART group (P=0.040 and 0.047, respectively). At 6mo after surgery, the MTF cutoff was statistically significant different between the two groups (P=0.026). No significant difference in SR between the FS-LASIK and SMART groups was observed at 1, 3, and 6mo postoperatively (P>0.05). CONCLUSION: The HOAs increase and visual quality is delayed in both groups postoperatively, and the long-term objective visual quality after SMART is slightly better than that after FS-LASIK.

The prevalence of vision impairment and refractive error in 3654 first year students at Tianjin Medical University.

AIM: To determine the prevalence of vision impairment (VI) and refractive error in first year university students at the Tianjin Medical University. METHODS: This is a cross-sectional observational cohort study of VI and refractive error among first year university students at the Tianjin Medical University. The first year university students were involved in this study and were given a detailed questionnaire including age, birth date, and spectacle wearing history. A standardized ophthalmologic examination including visual acuity (VA), slit-lamp examination, non-cycloplegic auto-refraction, objective refraction, fundus photography, and examination of their spectacles were recorded. RESULTS: A total of 3654 participants were included in this study. Totally 3436 (94.03%) individuals had VI in this population. Totally 150 (4.10%) individuals had VI due to ocular disease, including amblyopia, congenital cataract, retinal atrophy or degeneration, strabismus, congenital nystagmus, refractive surgery orthokeratology. Totally 3286 (89.93%) subjects had VI due to refractive error. Only 218 (5.97%) students were emmetropia. Moreover, refractive error was the main cause for the VI (95.63%). Totally 3242 (92.52%) students were myopia and the prevalence of mild, moderate, and high myopia subgroup was 27.05%, 44.35%, and 21.26% respectively. Totally 44 (1.29%) subjects were hyperopic. The rates of uncorrected visual acuity (UCVA), presenting visual acuity (PVA) and best corrected visual acuity (BCVA) which better than 20/20 in both eyes were 5.65%, 22.32% and 82.13% respectively. The rates of correction, under correction and well correction in myopia subjects were 82.73%, 84.39% and 15.61%, respectively. CONCLUSION: We present a high prevalence of refractive errors and high rates of under correction refractive error among first year university students. These results may help to promote vision protection work in young adults.

Clinical evaluation of surgery-induced astigmatism in cataract surgery using 2.2 mm or 1.8 mm clear corneal micro-incisions.

AIM: To evaluate corneal astigmatism after phacoemulsification using 2.2 mm or 1.8 mm clear corneal micro-incisions and its effects on visual function. METHODS: Sixty cases (60 eyes) with cataract were randomly divided into groups A (n=30) and B (n=30) respectively underwent 2.2 mm and 1.8 mm clear corneal tunnel incision phacoemulsification combined with folding intraocular lens implantation from the time direction of 11:00. On day 1 and at 1, 4, and 6wk after operation, patients' vision was measured and both the corneal curvature and corneal thickness (CT) were recorded using Pentacam. RESULTS: The measured surgery-induced astigmatism (SIA) in both groups A and B peaked on day 1 after operation, and then gradually decreased and eventually stabilized in week 4. No statistically significant difference was found in corneal astigmatism between two groups (P>0.05). The measured corneal astigmatism at 4wk and 6wk postoperatively were 0.28±0.09 D and 0.27±0.10 D for groups A and 0.27±0.09 D and 0.25±0.10 D for groups B without statistically significant difference (P>0.05). In addition, no significant differences in visual acuity and CT were found between groups A and B before or after operation. CONCLUSION: Both 2.2 mm and 1.8 mm micro-incision cataract surgeries result in relatively small SIA with no difference in visual function and corneal astigmatism between two surgery approaches. Thus, the two types of surgical systems are safe and efficient for cataract treatment, by which satisfactory uncorrected visual acuity can be regained early postoperatively.

Anti-VEGF treatment for myopic choroid neovascularization: from molecular characterization to update on clinical application.

Choroidal neovascularization (CNV) secondary to pathologic myopia has a very high incidence in global, especially in Asian, populations. It is a common cause of irreversible central vision loss, and severely affects the quality of life in the patients with pathologic myopia. The traditional therapeutic modalities for CNV secondary to pathologic myopia include thermal laser photocoagulation, surgical management, transpupillary thermotherapy, and photodynamic therapy with verteporfin. However, the long-term outcomes of these modalities are disappointing. Recently, intravitreal administration of anti-VEGF biological agents, including bevacizumab, ranibizumab, pegaptanib, aflibercept, and conbercept, has demonstrated promising outcomes for this ocular disease. The anti-VEGF regimens are more effective on improving visual acuity, reducing central fundus thickness and central retina thickness than the traditional modalities. These anti-VEGF agents thus hold the potential to become the first-line medicine for treatment of CNV secondary to pathologic myopia. This review follows the trend of "from bench to bedside", initially discussing the pathogenesis of myopic CNV, delineating the molecular structures and mechanisms of action of the currently available anti-VEGF drugs, and then systematically comparing the up to date clinical applications as well as the efficacy and safety of the anti-VEGF drugs to the CNV secondary to pathologic myopia.

Nerve growth factor expression and nerve regeneration in monkey corneas after LASIK.

PURPOSE: To determine whether changes in cornea nerve growth factor (NGF) protein and gene expression correlate with corneal nerve regeneration after LASIK in rhesus monkeys. METHODS: Ten rhesus monkeys underwent randomly assigned LASIK procedures to correct -8.0 diopters of myopia in both eyes and two additional monkeys (with no surgery) served as controls. The central corneas of the experimental animals were excised 3 and 7 days and 1, 3, and 6 months after the surgery. Nerve regeneration, NGF mRNA, and protein expression were analyzed by gold chloride staining, real-time polymerase chain reaction, and enzyme-linked immune sorbent assay analysis, respectively. RESULTS: Compared to controls, the LASIK-treated animals had a significantly diminished nerve plexus in the sub-basal region of the cornea at all times after the surgery (P < .001). NGF protein levels decreased significantly on days 3 and 7 after LASIK (P < .001), but returned to control levels 1 month later. NGF mRNA levels increased 5.4-fold on day 3 after the surgery (P < .001), then reduced to two-fold (P < .05) above control levels on day 7 and were back to normal at 3 months and beyond. After LASIK, the changes of early NGF protein and NGF mRNA levels correlated with the density of the corneal nerve plexuses. CONCLUSIONS: The results showed that the LASIK procedure in non-human primates was associated with changes in NGF protein and mRNA levels in the cornea. Such changes may be related to the initiation of nerve regeneration and the final recovery of nerve plexuses in the cornea.

[Clinical research of the phakic foldable angle-supported intraocular lens for the correction of high myopia].

OBJECTIVE: To assess the safety, efficacy, predictability and stability of the phakic foldable angle-supported intraocular lens (IOL) (CACHET IOL, Alcon Inc., USA.) for correction of high-to-extremely high myopia in adults. METHODS: In this prospective study, 29 eyes of 15 patients were implanted with CACHET phakic angle-supported IOL and followed for 1 year postoperatively. Preoperative manifest refractive sphere was -12.08 ± 2.44 diopters (D). Visual acuity(uncorrected visual acuity, UCVA; best spectacle-corrected visual acuity, BSCVA), predictability and stability of manifest refraction spherical equivalent (MRSE), adverse events, and endothelial cell density were analyzed primarily during 1-year of follow-up. RESULTS: After 1 year of follow-up, a BSCVA of 0.6 or better was achieved by 100% of eyes; 9.7% (26/29) had a BSCVA of 1.0 or better; no eyes lost ≥ 1 line BSCVA, 62.1%(18/29) had no change in lines of BSCVA, 31.0% (9/29) gained 1 line of BSCVA, 3.4% (1/29) gained 2 line of BSCVA, and 3.4% (1/29) gained more than 2 line of BSCVA; the safety index was 1.13 (1.08/0.96); UCVA of 1.0 or better was achieved by 58.6% (17/29), 100% had an UCVA of 0.5 or better, 86.2% (25/29) of eyes achieved a UCVA of 0.8 or better, and 93.1% (27/29) of eyes achieved a UCVA of 0.6 or better; the efficacy index was 1.03(0.99/0.96). The overall mean percentage change in endothelial cell density 1 year after surgery was -0.23% ± 4.80%. Five eyes (17.2%) had increased intraocular pressure (IOP) on the day of surgery. No pupil ovalization, pupillary block, or retinal detachment events were observed. Glare (6.9%, 2/29) and halo (13.8%, 4/29) mainly appeared in the first month after surgery, and had no influence on driving in night. CONCLUSIONS: After 1 year of follow-up, the implantation of phakic foldable angle-supported IOL was proved to be safe, effective and predictable with minimal complications in patients with high myopia. Due to the limitation of visiting time, long-term of clinical investigation is necessary to verify the safety and efficacy of this IOL.

[Research status of photodynamic therapy for corneal neovascularization].

Pathological corneal neovascularization is an important reason of visual impairment. Research outcomes showed that angiogenesis mechanism is similar in all the tissues of the body and photodynamic therapy demonstrate a useful effect in blocking tumor and choroidal neovascularization. This method is currently being tried for the treatment of corneal neovascularization. This paper will review the research status of photodynamic therapy in corneal neovascularization using various photosensitizers.

[Coverage on cataract surgery among adults aged 40 or above in a multiethnic rural district of high altitude area in Gongshan county, Yunnan province, China].

OBJECTIVE: To estimate the prevalence of cataract and its surgical coverage rate together with the burden related to bilateral cataract-blindness, among adults aged 40 or above in Gongshan county of Yunnan province and to evaluate the current cataract status and the efficacy of local cataract prevention program. METHODS: Cluster sampling was used. The protocol consisted of personal interview, pilot study, visual acuity checking, measuring the intraocular pressure; slit lamp microscopy and the fundus of the eye examination etc. Cataract was graded clinically using the Lens Opacity Classification System (LOCS) III. Bilateral cataract-blindness burden, bilateral cataract-blindness burden and cataract surgical coverage rate were calculated respectively, using two different criteria. Odds ratios (OR) were compared among different groups regarding age, gender, education, ethnic group and altitude of living area. RESULTS: Among the 1236 eligible residents, 1116 (90.3%) were enrolled in the present study. The prevalence of cataract was 23.8% among adults aged 40 or order. When the bilateral best refractive vision<3/60 was defined as the blindness criterion, the bilateral cataract-blindness burden showed as 1.3%, and cataract blindness surgical coverage rate was 50.0%. When the bilateral presenting vision<6/60 was defined as the blindness criterion, the bilateral cataract-blindness burden was 25.0%, and cataract blindness surgical coverage rate was 12.9%. The cataract surgical coverage rates were much lower and the bilateral cataract-blindness burden much higher in women, illiterates, living in high altitude areas and those who were aged 70 or above. CONCLUSION: Cataract blindness was a serious public health problem in aged individuals and illiteracy in the residents of the studied areas. Poor prevention programs on cataract called for urgent action to be taken.

Comparison of disposable sutureless silicone ring and traditional metal ring in 23-gauge vitrectomy combined with cataract surgery.

BACKGROUND: The purpose of this prospective, interventional, comparative case series was to evaluate the efficiency and feasibility of a disposable sutureless silicone lens ring for corneal contact lens stabilization during combined 23-gauge vitrectomy and cataract surgery. METHODS: We developed a ring consisting of a single silicone component with three footplates along the ring margin to fit cannulae for holding conventional contact lenses. Thirty eyes from 30 patients with cataract and vitreoretinal disease were included, and divided into two matched groups according to disease type and ring used. In Group A, we used a 23-gauge transconjunctival vitrectomy system and a disposable sutureless silicone lens ring (n = 15). In Group B, we used a 23-gauge transconjunctival vitrectomy system and a conventional metal lens ring (n = 15). The main outcome measures were: time required for vitrectomy preparation, rate of intraoperative corneal limbus bleeding, and limbus scar rate at the final follow-up visit. RESULTS: Thirty cases were successfully completed. The average vitrectomy preparation time was less in Group A than in Group B (P < 0.01), and the average preparation time saved was 3.94 minutes. None of the Group A patients had intraoperative bleeding or postoperative scarring, whereas all 15 Group B cases had bleeding and five had scarring. There was a statistically significant difference between Group A and Group B for these complications (P ≤ 0.05). CONCLUSION: This report demonstrates the advantages of using a sutureless silicone ring during combined 23-gauge vitrectomy and cataract surgery. Using this method could allow extra time for the surgeon to pay more attention to complex vitreoretinal procedures.

Incidence and characteristics of unilateral keratoconus classified on corneal topography.

PURPOSE: To evaluate the characteristics of unilateral keratoconus defined on the basis of corneal topography and analyze videokeratography parameters between fellow eyes and normal controls. METHODS: A total of 111 patients with clinical keratoconus were prospectively enrolled. Both eyes were evaluated with Tomey (Tomey Corp) and Orbscan II (Bausch & Lomb) corneal topography systems. The patient was classified as having unilateral keratoconus if one eye had clinical keratoconus and the other eye did not have any topographic signs of keratoconus such as asymmetric videokeratographic pattern, positive result in Tomey keratoconus screening, maximum posterior elevation >40 µm, or corneal thinnest pachymetry <500 µm. Clinical characteristics and 13 Orbscan II quantitative indices between keratoconic and fellow eyes and normal control eyes were evaluated. RESULTS: Five (4.5%) of 111 patients with keratoconus had no topographic evidence of keratoconus in the fellow eye. All clinically normal fellow eyes had symmetric bowtie patterns. Statistically significant differences were noted in maximum posterior elevation, corneal irregularity, and corneal thinnest values between keratoconic eyes and fellow eyes, and between keratoconic eyes and control eyes. Only 3-mm irregularity was significantly higher in the fellow eyes compared with control eyes (P<.05). An increased trend for corneal 5-mm irregularity was found in fellow eyes compared to control eyes. CONCLUSIONS: The incidence of unilateral keratoconus was 4.5%. A trend of higher irregularity was found in fellow eyes compared with control eyes. This finding indicates that fellow eyes may show a certain low-expressivity morphologic feature of keratoconus.

Adeno-associated virus-mediated IL-10 gene transfer suppresses lacrimal gland immunopathology in a rabbit model of autoimmune dacryoadenitis.

PURPOSE: To evaluate the effect of adeno-associated virus (AAV) vector-mediated viral (v)IL-10 gene expression on lacrimal gland (LG) immunopathology and ocular surface disease in a rabbit model of induced autoimmune dacryoadenitis (ID). METHODS: Autologous peripheral blood lymphocytes, activated in a mixed-cell reaction when cocultured with purified rabbit lacrimal epithelial cells, induce a Sjögren's-like autoimmune dacryoadenitis when injected directly back into the donor animal's inferior LG. Four weeks after disease induction, AAV vector expressing the vIL-10 gene under control of a tetracycline-inducible promoter was injected into the inferior LG of the treatment group (ID/Rx), and doxycycline was fed orally to induce transgene expression. The ID group serving as control also received doxycycline. All LGs were removed 16 weeks after disease induction. RESULTS: Clinical symptoms showed overall improvement in the ID/Rx group compared with the ID group. Histopathologic examination of the ID group's LG revealed scattered large lymphocytic foci and areas of altered or distorted acini, whereas the ID/Rx group had scattered small lymphocytic foci. The number of CD18(+) cells was almost fivefold lower in the ID/Rx group than in the ID group. Although the total number of RTLA(+) cells did not differ between the groups, the CD4/CD8 ratio was 16-fold smaller in the ID/Rx group. CONCLUSIONS: Animals with experimentally induced autoimmune dacryoadenitis appeared to benefit from AAV-mediated vIL-10 gene transfer therapy. Quantitative immunohistochemical analysis suggested that the therapy might not have been simply immunosuppressive but rather supported the induction of CD8(+) regulatory cells.

Evaluation of higher order ocular aberrations in patients with keratoconus.

PURPOSE: To describe higher order ocular aberrations in eyes with keratoconus. METHODS: Prospective, observational, case-control study comparing higher order ocular aberrations in patients with keratoconus with control subjects with myopia. RESULTS: One hundred sixteen patients with keratoconus were recruited. Data were analyzed in 35 keratoconus eyes, 38 keratoconus suspect eyes, and 166 right eyes with myopia. Mean total higher order root-mean-square (RMS) values (3rd to 5th order) were 1.73 +/- 0.71 microm in eyes with keratoconus, 0.94 +/- 0.66 microm in eyes with keratoconus suspect, and 0.49 +/- 0.16 microm in control eyes. Keratoconus eyes had greater total higher order RMS, 3rd to 5th order RMS, and RMS for all Zernike terms than those in the control group (P < .001). CONCLUSIONS: Keratoconus and keratoconus suspect eyes had significantly larger higher order aberrations in total higher order RMS and 3rd order RMS than control eyes.

Evaluation of keratoconus in Asians: role of Orbscan II and Tomey TMS-2 corneal topography.

PURPOSE: To evaluate the corneal topographic patterns of Asian patients with keratoconus (KC). DESIGN: Prospective observational case-control study. SETTING: Institutional. STUDY POPULATION: A total of 116 patients (both eyes included) with KC were recruited. The control group consisted of 70 laser in-situ keratomileusis (LASIK) candidates with myopia. Patients with previous ocular surgery and trauma were excluded. OBSERVATION PROCEDURE: Corneal topography was performed using the Tomey KC screening system (Topographic Modeling System, software version 2.4.2J, Tomey Corp, Nagoya, Japan) and Orbscan II corneal topography system (Bausch & Lomb Surgical, Orbtek Inc, Salt Lake City, Utah, USA). MAIN OUTCOME MEASURES: Videokeratographic variables were analyzed and the eyes were grouped into KC, KC suspect, and control groups. RESULTS: The corneal topographic patterns of 196 eyes were analyzed. The topographic patterns displayed by Tomey (TMS-2N) and Orbscan II were similar. The majority of eyes with KC (71.2%) and KC suspect (70%) had asymmetric bowtie patterns. Thirteen indices of TMS-2N were analyzed and the means of the indices were found to be significantly higher in eyes in the KC group than the KC suspect group (P < .001). Fourteen indices of Orbscan II were analyzed. Eyes in the KC suspect group had higher mean posterior elevation (46 +/- 17 microm), 3 mm irregularity (2.44 +/- 1.36 diopters [D]), 5 mm irregularity (2.61 +/- 1.19 D) and had thinner corneas (mean 504.4 +/- 40.4 microm) than normal eyes (26 +/- 8 microm, 1.05 +/- 0.37 D, 1.38 +/- 0.39 D, and 554.0 +/- 25.0 microm, respectively). CONCLUSION: Corneal topography pattern recognition combined with quantitative diagnostic indices is useful for the screening and classification of KC with the Orbscan II being more sensitive in screening for KC than TMS-2N.

Higher order ocular aberrations in eyes with myopia in a Chinese population.

PURPOSE: To describe the characteristics of higher order ocular aberrations of adult Chinese eyes with myopia. METHODS: Higher order aberrations in consecutive right eyes of 166 Chinese patients with myopia who enrolled for preoperative assessment for LASIK were retrospectively reviewed. Wavefront aberrations were measured with the Bausch & Lomb Zywave over a 6-mm dilated pupil. The correlations between higher order aberrations and myopia, astigmatism, and age, respectively, were analyzed. RESULTS: Mean patient age was 32.1 +/- 6.2 years, the mean refractive error was sphere -5.23 +/- 1.79 diopters (D) and cylinder -1.29 +/- 0.98 D. The mean of the total higher order root-mean-square (RMS) (third to fifth order) was 0.49 +/- 0.16 microm. Third-order RMS was largest (mean 0.37 +/- 0.16 microm), followed by fourth-order RMS (mean 0.29 +/- 0.11 microm). For individual higher order Zernike coefficients, spherical aberration (C4(0)) predominated with a mean of 0.23 +/- 0.14 microm. No correlation was found between total higher order RMS and myopia or between total higher order RMS and age. Small but statistically significant relationships were found in the following groups: age and vertical primary coma (C3(-1))(r=-0.206, P=.008); age and spherical aberration (C4(0)) (r=0.196, P=.012); and myopia and horizontal trefoil (C3(3)) (r=-0.158, P=.042). CONCLUSIONS: Higher order aberrations varied among individuals with myopia. Third-order RMS was the predominant higher order aberration. Spherical aberration and vertical primary coma increased slightly with age. Our study helps establish ocular aberration standards for Chinese refractive surgery candidates.

Evaluation of Orbscan II corneal topography in individuals with myopia.

PURPOSE: To evaluate Orbscan II (Bausch & Lomb, Orbtek Inc., Salt Lake City, UT) corneal topography in individuals with myopia. DESIGN: Retrospective, observational, consecutive, clinical case series. PARTICIPANTS: One hundred forty eyes of 70 persons with myopia. METHODS: Manifest refraction results and the Orbscan II corneal topographic maps were reviewed retrospectively. MAIN OUTCOME MEASURES: Refractive powers and the following test indices produced by Orbscan II were analyzed: anterior elevation best-fit sphere (BFS), posterior elevation BFS, maximum posterior elevation (Max PE), radius of Max PE, maximum keratometry, minimum keratometry, astigmatism, 3-mm irregularity, 3-mm mean power, 3-mm astigmatism, 5-mm irregularity, 5-mm mean power, 5-mm astigmatism, corneal diameter, pupil diameter, thinnest pachymetry, and anterior chamber depth. The correlations between right eyes and left eyes and between indices were explored. RESULTS: Of the 140 eyes, the mean manifest refraction was -5.27+/-2.19 diopters (D; range, -10.50 to 0.00 D), the mean Max PE was 28+/-7 mum, and the mean maximum keratometry was 44.5+/-1.5 D. Correlation coefficient analyses of Orbscan II quantitative indices combined with pattern recognition showed that there were high degrees of correlations between the right and left eyes of each individual patient. Maximum posterior elevation, corneal irregularity, and thinnest pachymetry did not vary with the degree of maximum keratometry. CONCLUSIONS: This article provides a detailed description and analysis of Orbscan II corneal topography of a normal population with myopia. This helps in establishing normal standards in Orbscan II corneal topography that will aid in preoperative assessment in refractive surgery.