LASIK versus PRK for high astigmatism

Purpose

To compare the refractive outcomes of laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) for myopic astigmatism of 3 diopters (D) or more.

Study design

Retrospective matched comparative study.

Methods

This study include consecutive myopic patients (SE 0 to –10 D) undergoing LASIK or PRK between 2007 and 2016 with astigmatism of 3 to 6 D, and postoperative follow-up of at least 30 days for LASIK and 60 days for PRK, compared outcomes of LASIK and PRK eyes.

Results

The LASIK and PRK groups comprised 175 eyes of 175 patients each, with median follow-up of 39 and 139 days, respectively (P?<?0.001). Mean preoperative manifest astigmatism was –3.35?±?0.46 and –3.42?±?0.51 D (P?=?0.92), postoperative SE was –0.43?±?0.55 and –0.16?±?0.64 D (P?<?0.001), and arithmetic astigmatism was –0.59?±?0.46 and –0.88?±?0.60 D (P?<?0.001), for the LASIK and PRK groups, respectively. Fifty-seven and 64.0% eyes had postoperative SE within?±?0.5 D of emmetropia (P?=?0.19), and 57.7 and 38.8% eyes were within 0.5 D of attempted astigmatic correction (P?<?0.001) for the LASIK and PRK groups, respectively. More PRK eyes were overtreated regarding both SE and astigmatism than LASIK eyes (P?<?0.001). The efficacy and safety indices were close to 1.0 in both groups. The surgically induced astigmatism, magnitude of error, index of success, correction index and flattening index were all better in the LASIK group.

Conclusion

Both LASIK and PRK achieve good outcomes in high astigmatism. LASIK achieved mild superiority over PRK.

     

Detachment of subfoveal choroidal neovascularization in age-related macular degeneration

PURPOSE: To report the entity of partial detachment and folding of subfoveal choroidal neovascularization (CNV) in age-related macular degeneration (ARMD). DESIGN: Interventional case reports. METHODS: Review of the features of CNV detachment in two patients with CNV due to ARMD by contact lens slit-lamp biomicroscopy, fluorescein angiography, optical coherence tomography, and three-dimensional confocal scanning laser indocyanine green (ICG) angiography. RESULTS: One patient out of approximately 300 (0.5%) ARMD patients treated by photodynamic therapy (PDT) developed partial CNV detachment and folding 6 weeks after the second PDT treatment. Another patient out of approximately 100 (1.0%) ARMD patients treated by transpupillary thermotherapy (TTT) developed partial CNV detachment and folding 6 weeks after the second TTT treatment. The CNVs were large (2,500 microm to 4,500 microm) and located between the retina and the retinal pigment epithelium. In each, these findings were clearly visualized by slit-lamp biomicroscopy. Fluorescein angiography demonstrated an associated retinal pigment epithelium tear in one patient. Optical coherence tomography showed distinctive features and confocal scanning laser ICG further delineated the detached folded CNV. The best-corrected visual acuity improved in one patient from 20/80 to 20/40 and in the other from counting fingers at 6 feet to 20/200 after the CNV detachment. CONCLUSIONS: Partial CNV detachment and folding represent a unique, not previously reported, and possibly favorable outcome of PDT and TTT. The low energy and selectivity of these treatments may explain this phenomenon.     

Geographic variation in groundwater iodine and iodine deficiency in Israel, The West Bank and Gaza

BACKGROUND: Iodine deficiency during pregnancy and infancy is the world's most common preventable cause of mental retardation. Previous studies have shown a high incidence of goiter and low groundwater iodine concentrations in northern Israel. OBJECTIVE: We examined the relationship between low groundwater iodine and iodine deficiency in pregnant women and schoolchildren. SUBJECTS AND METHODS: We measured the urinary iodine excretion of school-children in the West Bank and Gaza and rural and urban pregnant women in Western Galilee (an area known to have low groundwater iodine concentrations). We also measured iodine concentrations in groundwater in various locations in the West Bank and Gaza. RESULTS: Lower urinary iodine excretion was found among pregnant Arab women living in rural Western Galilee (101+/-7 microg iodine/g creatinine). 20% of them excreted <50 microg I/g creatinine. This is relatively less than found among pregnant Jewish women living in cities in the same area (154+/-13 microg I/g creatinine). Low iodine concentrations (<5 microg/l) were found in groundwater in the Nablus, Ramallah, Bethlehem highlands, as compared to normal concentrations in the lowland districts of the West Bank and Gaza. In a cohort of 728 schoolchildren aged 8-10, 10% (range 8-13%) of children from areas of low groundwater iodine had low levels of urinary iodine excretion, as compared to only <5% of those from districts with groundwater iodine concentrations >10 microg/l. CONCLUSIONS: Lower concentrations of groundwater iodine are related to low urinary iodine excretion in Israel, the West Bank and Gaza.     

Contrast sensitivity after wave front-guided LASIK

PURPOSE: To compare the effects on contrast sensitivity of wave front-guided (WFG) versus standard LASIK. DESIGN: Prospective, nonrandomized, comparative clinical study. PARTICIPANTS: Twenty-four eyes of 13 consecutive patients (mean age, 25.2+/-8.4 years; spherical equivalent, -0.5 to -4.25 diopters [D]) treated with WFG LASIK (WaveLight-Allegretto scanning-spot laser and wave front analyzer) and 22 eyes of 12 consecutive patients (mean age, 28.4+/-9.1 years; spherical equivalent, -0.75 to -4.5 D) treated with standard LASIK (WaveLight-Allegretto scanning-spot laser). METHODS: Best-corrected contrast sensitivity was measured before and 1 month after surgery in both the WFG LASIK group and the standard LASIK group. A sine-wave contrast sensitivity test (functional acuity contrast test) was used to measure contrast sensitivity at 5 spatial frequencies (1.5, 3, 6, 12, and 18 cycles/degree). We compared the LASIK-induced changes in contrast sensitivity in each groups at each spatial frequency. MAIN OUTCOME MEASURE: The effect on contrast sensitivity of WFG LASIK versus standard LASIK. RESULTS: Uncorrected visual acuity of 20/20 or better was achieved by 72% of eyes treated with WFG LASIK and by 70% of the eyes treated with standard LASIK. One month after LASIK, 88% of the contrast sensitivity measurements improved in the WFG LASIK group, whereas in the standard LASIK group, only 40% of the contrast sensitivity measurements improved. The contrast sensitivity improvement was significantly larger in the WFG LASIK group at all spatial frequencies (P<0.05). The WFG LASIK patients had a negative correlation between the changes in contrast sensitivity and the preoperative refractive error. CONCLUSIONS: The ability of WFG LASIK to correct optical aberrations results in significantly improved contrast sensitivity compared with standard LASIK 1 month after surgery.     

Mortality attributable to tobacco use in Canada and its regions, 1994 and 1996

Using data from the National Population Health Survey and the Canadian Mortality Database, we applied the Smoking-Attributable Mortality, Morbidity and Economic Cost method to estimate national and regional smoking-attributable mortality for 1994 and 1996. The results indicate that 29,229 men and 15,986 women died in 1996 as a result of smoking, including 105 children under the age of 1. This total of approximately 45,200 deaths represents an increase of 3,807 deaths since 1991, of which 2,445 occurred in women. The increase in female mortality is almost entirely due to adult diseases, divided between cancers (1,026), cardiovascular diseases (743) and respiratory diseases (870).     

Outcomes of photorefractive keratectomy in patients with posterior corneal steepening

PurposeTo assess post-operative outcomes following photorefractive keratectomy (PRK) in patients with posterior corneal steepening compared to an age, gender and refraction matched control group.MethodsA retrospective matched case-control study that analysed outcomes of PRK in eyes with posterior corneal steepening as shown by the Sirius tomography (Sirius, CSO, Italy), versus normal eyes. Both groups were age, gender and refraction matched. Data collected include: demographic data, pre-operative and post-operative refraction, uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA), maximal ablation depth. Inferior–superior ratio, central corneal thickness (CCT), mean posterior keratometry (K), Baiocchi Calossi Versaci index for the front (BCV_f) and back (BCV_b) cornea, the symmetry index of front (SI_f) and back (SI_b) corneal curvature were assessed pre- and postoperatively.ResultsOverall, 89 study eyes and 954 normal myopic eyes were included. Compared to the control group, corneas with posterior steepening demonstrated significantly reduced CDVA (p < 0.0001 and p = 0.007) and lower CCT (p < 0.0001 and p = 0.03), before and following the operation, respectively. Pre-operative BCV_f, BCV_b, SI_f and SI_b were significantly higher in corneas with posterior steepening (p < 0.0001) and remained higher following the surgery except for BCV_f. Ectasia occurred in one eye (1.1%). The safety and efficacy indices at 12 months were comparable for both groups.ConclusionPRK on corneas with posterior steepening results in similar refractive outcomes compared to normal eyes, 1 year following the surgery. Keratectasia is a rare, however a possible complication.Subject terms: Outcomes research, Corneal diseases     

Dry eye in diabetic patients

PURPOSE: To compare the prevalence of keratoconjunctivitis sicca (KCS) in a prospective cohort of 22,382 diabetic patients with that in the general population. DESIGN: Prospective, observational, cohort study. METHODS: Setting: A district of israel's largest health maintenance organization. STUDY POPULATION: We followed the electronic medical records of all patients in the district older than 50 years (159,634 patients) between January 1 and December 31, 2003. Of those, 22,382 (14.0%) had diabetes. OBSERVATION PROCEDURE: The proportion of ocular lubrication consumers was compared among diabetic and nondiabetic patients. All HbA1c laboratory tests performed by the diabetic patients were documented (41,910 tests), and glycemic control was correlated with the consumption of ocular lubrication. MAIN OUTCOME MEASURES: Ocular lubrication use by diabetic patients compared with the general population and the relationship between glycemic control and ocular lubrication use. RESULTS: After age and gender adjustment, a significantly higher percentage of diabetic patients (20.6%) received ocular lubrication, compared with nondiabetic patients (13.8%, P < .001). The difference was significant for all age groups and for both sexes (P < .001). A similar significant difference was prominent between diabetic and nondiabetic patients aged 60 to 89 years who were frequent users of ocular lubrication. Ocular lubrication consumption increased with poorer glycemic control (mean annual HbA1c levels). Multivariate analysis revealed this effect to be independent of age, sex, place of birth, or place of residence. CONCLUSIONS: KCS is significantly more common among diabetic patients. Poor glycemic control correlates with increased artificial tear use in diabetic patients.