Intraocular lens power calculation in keratoconus; a review of literature

Purpose: To review the published literature regarding cataract surgery in keratoconus (KCN) patients with emphasis on challenges encountered during intraocular lens (IOL) power calculation and their solutions. Methods: A literature review was performed to investigate all the relevant articles on the advancements of IOL calculations in KCN patients. Results: Cataract surgery in keratoconic eyes can improve patients' refraction, and proper patient selection and IOL calculation methods are necessary to get the best results. The main problem in KCN patients is unreliable biometric measurements. It is more difficult to make conclusions in more advanced keratoconic corneas, as the steep keratometric values in these eyes will result in the selection of a low-power IOL. Presence of a low-power IOL will yield in extreme postoperative hyperopia, and IOL exchange might be mandatory. In cases in which keratoplasty may be needed in the future, contact lens fitting can help surgeons make a better decision preoperatively. Axial length (AL) measurements may have better repeatability and reproducibility than keratometry (K) readings in keratoconic eyes. SRK II formula may provide the most accurate IOL power in mild KCN. There is still not a comprehensive consensus of which formula is the best one in moderate and severe KCN, as the literature is limited in this subject. Conclusions: Various methods of IOL power calculation optimization and recommendations may hold the key to improve surgical outcomes in keratoconic eyes. There are multiple sources of biometric error in KCN patients, hence IOL calculation methods may not be as efficient as expected in these eyes. © 2019 Iranian Society of Ophthalmolog

Oral azithromycin versus doxycycline in meibomian gland dysfunction: A randomised double-masked open-label clinical trial

Background/aims: To assess the efficacy and safety of oral azithromycin compared with oral doxycycline in patients with meibomian gland dysfunction (MGD) who had failed to respond to prior conservative management. Methods: 110 patients (>12 years old) with MGD were randomly assigned to receive either oral 5-day azithromycin (500 mg on day 1 and then 250 mg/day) or 1-month doxycycline (200 mg/day). They also continued eyelid warming/cleaning and artificial tears. A score comprising five symptoms and seven signs (primary outcome) was recorded prior to treatment and at 1 week, and 1 and 2 months after treatment. Total score was the sum of both scores at each follow-up. Side effects were recorded and overall clinical improvement was categorised as excellent, good, fair or poor based on the percentage of change in the total score. Results: Symptoms and signs improved significantly in both groups (p=0.001). While improvement of symptoms was not different between the groups, bulbar conjunctival redness ( p=0.004) and ocular surface staining (p=0.01) were significantly better in the azithromycin group. The azithromycin group showed a significantly better overall clinical response ( p=0.01). Mild gastrointestinal side effects were not significantly different between the groups except for the second visit, when the doxycycline group had significantly more side effects (p=0.002). Conclusions: Although both oral azithromycin and doxycycline improved the symptoms of MGD, 5-day oral azithromycin is recommended for its better effect on improving the signs, better overall clinical response and shorter duration of treatment. Trial registration number: NCT01783860. © 2015, BMJ Publishing Group. All rights reserved

Occurrence of fumonisins in maize imported into Iran during 2001-2002

ArticleFumonisins, fungal toxins found primarily in maize and produced by various Fusarium species, have been shown to cause a variety of significant adverse health effects in livestock and experimental animals, and are probable human carcinogens. Thirty-three maize samples were collected at ports from bulk shipments, which were imported into Iran from six countries during 2001-2002, and analysed by HPLC for the most abundant of the naturally occurring fumonisin analogues, namely fumonisins B1 (FB1), B2 (FB2) and B3 (FB3). Of the 33 samples, 21 (64%) were found to contain FB1 (58-512 μg/kg) at levels above 10 μg/kg. The frequency of FB1 found in maize samples imported from Uruguay and Canada was 75%, followed by China and Argentina (67%), USA (60%), and Brazil (50%). The average FB1 level was 266 and 169 μg/kg for positive and all samples, respectively. Medians were 250 and 146 μg/kg for positive and all samples, respectively. FB2 levels ranged from not detected (<10 μg/kg) to 53 μg/kg, whereas no sample had an FB3 level above the detection level (10 μg/kg). This is the first report of fumonisin contamination of imported maize in Iran. Although, the level of all detected fumonisins were below the Iranian and FDA tolerance levels for foods and feeds, It is necessary to maintain the strict rules to ensure continued safety of imported maize

Long-term outcomes of posterior chamber phakic intraocular lens implantation in keratoconus

Background: In this retrospective observational case series study, the aim was to evaluate the long-term safety, efficacy, stability and predictability of posterior chamber phakic intraocular lens (pIOL) implantation to correct myopia and myopic astigmatism associated with keratoconus. Methods: Uncorrected distance visual acuity (UDVA), best spectacle-corrected distance visual acuity (BSCDVA), refraction and adverse effects were evaluated in 23 keratoconic eyes of 13 patients after fiveyears with Visian ICMV4 pIOL (STAAR Surgical). Results: The mean pre-operative spherical equivalent and cylinder changed from -5.35 ± 2.82 D and -3.14 ± 1.58 D to -0.78 ± 1.31 D and -1.56 ± 1.53 D, respectively, fiveyears post-operatively. Before the surgery the mean Snellen decimal BSCDVA was 0.60 ± 0.20. The mean UDVA and BSCDVA changed to 0.74 ± 0.22 and 0.88 ± 0.16, respectively. A total of 82.5per cent of eyes achieved 6/12 or better UDVA post-operatively. The mean safety and efficacy indices were respectively, 1.47 ± 0.32 and 1.24 ± 0.34. No eye lost a line of visual acuity and 19 eyes gained one or more lines. An endothelial cell loss of 7.88per cent occurred. No significant changes were seen in intraocular pressure, steep, flat and mean keratometry. The crystalline lens was clear. Conclusion: The clinical outcomes of the current study demonstrate the safety, efficacy and predictability of the implantable collamer lens (toric and non-toric) in the correction of myopia and myopic astigmatism associated with keratoconus. The patients' refractions achieved early stability and remained stable during the course of the study. © 2018 Optometry Australia

Long-term outcomes of posterior chamber phakic intraocular lens implantation in keratoconus

Background: In this retrospective observational case series study, the aim was to evaluate the long-term safety, efficacy, stability and predictability of posterior chamber phakic intraocular lens (pIOL) implantation to correct myopia and myopic astigmatism associated with keratoconus. Methods: Uncorrected distance visual acuity (UDVA), best spectacle-corrected distance visual acuity (BSCDVA), refraction and adverse effects were evaluated in 23 keratoconic eyes of 13 patients after five years with Visian ICMV4 pIOL (STAAR Surgical). Results: The mean pre-operative spherical equivalent and cylinder changed from �5.35 ± 2.82 D and �3.14 ± 1.58 D to �0.78 ± 1.31 D and �1.56 ± 1.53 D, respectively, five years post-operatively. Before the surgery the mean Snellen decimal BSCDVA was 0.60 ± 0.20. The mean UDVA and BSCDVA changed to 0.74 ± 0.22 and 0.88 ± 0.16, respectively. A total of 82.5 per cent of eyes achieved 6/12 or better UDVA post-operatively. The mean safety and efficacy indices were respectively, 1.47 ± 0.32 and 1.24 ± 0.34. No eye lost a line of visual acuity and 19 eyes gained one or more lines. An endothelial cell loss of 7.88 per cent occurred. No significant changes were seen in intraocular pressure, steep, flat and mean keratometry. The crystalline lens was clear. Conclusion: The clinical outcomes of the current study demonstrate the safety, efficacy and predictability of the implantable collamer lens (toric and non-toric) in the correction of myopia and myopic astigmatism associated with keratoconus. The patients� refractions achieved early stability and remained stable during the course of the study. © 2018 Optometry Australi

Human dietary exposure to fumonisin B1 from Iranian maize harvested during 1998-2000

ArticleFumonisin B(1) (FB(1)) is the most abundant of the fumonisin mycotoxins, mainly produced in maize by F. verticillioides and F. proliferatum. A previous study on the FB1 contamination of maize harvested in Mazandaran and Isfahan Provinces of Iran in 1998 and 1999 demonstrated contamination in both provinces. This present study was undertaken to further investigate the variation in levels of contamination and to estimate possible levels of human exposure to fumonisins in Iran. The mean level of FB(1) in 49 visually healthy maize samples collected from Mazandaran Province during 2000 was 6.14 mg/kg, which is higher than that found during 1998 and 1999 (2.27 and 3.18 mg/kg, respectively). Although these levels are higher than the Iranian legislative limits for fumonisins in maize intended for humans, the relatively low estimated consumption of maize in Iran (3.3 g/person/day) implies that average exposures (0.011 and 0.215 microg/kg body weight/day in Isfahan and Mazandaran, respectively) are within the provisional maximum tolerable daily intake of 2 microg/kg body weight/day set by the Joint FAO/WHO Expert Committee on Food Additives. Nevertheless, certain sections of the population who may consume higher amounts of maize or who may replace all or some of their consumption of other cereals with maize, could well exceed this limit.Research Department, Shaheed Beheshti University of Medical Sciences, I. R. Iran

Incidence of Fusarium verticillioides and levels of fumonisins in corn from main production areas in Iran

ArticleA total of 52 corn samples collected in 2000 from four main corn production provinces of Iran (Fars, Kermanshah, Khuzestan, and Mazandaran) were analyzed for contamination with Fusarium verticillioides and fumonisins (FB(1), FB(2), FB(3), and 3-epi-FB(3)). The mean incidence of F. verticillioides (percent of kernels infected) for these four areas was 26.7, 21.4, 24.9, and 59.0%, respectively. The incidence in Mazandaran was significantly (p < 0.05) above that of the other areas. All samples from Mazandaran were contaminated with fumonisins with a mean level of total fumonisins of 10674 microg/kg. In contrast, the incidence of fumonisin contamination above 10 microg/kg was 53 (8/15), 42 (5/12), and 57% (8/14) in the samples from Fars, Kermanshah, and Khuzestan, respectively, and the corresponding mean total fumonisin levels were 215, 71, and 174 microg/kg, respectively. No statistical differences (p > 0.05) were observed in the fumonisin levels of the corn samples from these three provinces, which were significantly (p < 0.05) lower than the fumonisin contamination in samples from Mazandaran