Medical Hypothesis, Discovery & Innovation (MEHDI) Journals
Not a member yet
182 research outputs found
Sort by
Micropulse Transscleral Cyclophotocoagulation: A Hypothesis for the Ideal Parameters
Full text linkMicroPulse transscleral cyclophotocoagulation (IRIDEX Corp., Mountain View, CA) is a novel technique that uses repetitive micropulses of active diode laser (On cycles) interspersed with resting intervals (Off cycles). It has been proposed that the OFF cycles allow thermal dissipation and, therefore, reduce collateral damage. The literature suggests that Micropulse has a better safety profile compared to traditional continuous-wave cyclophotocoagulation. However, because it is a relatively new technique, there are no clear guidelines stating the ideal laser parameters that would allow the best balance between high and sustained effectiveness with minimal side effects. This research reviewed the literature to approximate ideal parameters for single-session treatment. To simplify the comparison between studies, this study used Joules (J) as a way to standardize the energy levels employed. The reviewed clinical publications allowed reduction of these parameters to a range between 112 and 150 J of total energy, which allows a moderate IOP lowering effect of around 30% with few/no complications. An additional narrowing of the parameters was achieved after analyzing recently published experimental data. These data suggest a different mechanism of action for the Micropulse, similar to that of the pilocarpine. This effect was maximum at 150 J. Since clinical studies show few or no complications, even at those energy levels, it could be hypothesized that the ideal parameters can be located at a point closer to 150 J. This data also leads to the concept of dosimetry; the capacity to dose mTSCPC treatment based on desired IOP lowering effect and risk exposure. Further prospective studies are needed to test the proposed evidence-based hypothesis
Characteristics of Astigmatism after MyoRing Implantation
Full text linkConsidering the rising number of MyoRing implantation procedures in keratoconic corneas and the refractive outcomes associated with this treatment modality, this study aimed to evaluate and compare the magnitude and axis orientation of total and corneal astigmatism between before and after MyoRing implantation in 34 eyes of 28 patients with keratoconus (KCN) (mean age: 29.41 ± 7.0 years). The inclusion criterion was a reliable diagnosis of clinical KCN based on corneal biomicroscopic and tomographic findings. The mean total astigmatism of ocular refraction decreased significantly from -4.27 ± 3.15 D (before MyoRing implantation) to -2.18 ± 1.63 D (after MyoRing implantation) (P < 0.001). The mean astigmatism in the anterior and posterior surface of the cornea decreased significantly by 1.16 D (P = 0.001) and 0.24 D (P = 0.009), respectively, after MyoRing implantation. Before MyoRing implantation, the axis orientation of total ocular astigmatism for with-the-rule, oblique, and against-the-rule astigmatism was 21%, 42%, and 37%, respectively; at 6 months after MyoRing implantation, it was 18%, 24%, and 58%, respectively. Before MyoRing implantation, the axis orientation for with-the-rule, against-the-rule, and oblique astigmatism of the anterior surface of the cornea was 59%, 24%, and 17%, respectively; at 6 months after MyoRing implantation, it was 52%, 24%, and 24%, respectively. Before MyoRing implantation, the axis orientation of with-the-rule, oblique, and against-the-rule astigmatism of the posterior surface of the cornea was 68%, 29%, and 3%, respectively; at 6 months after MyoRing implantation, it was 67%, 12%, and 12%, respectively. MyoRing implantation significantly decreased the amount of total, anterior, and posterior corneal astigmatism
The Effect of Artificial Tear Preparations with Three Different Ingredients on Contrast Sensitivity in Patients with Dry Eye Syndrome
Full text linkThis study was conducted to investigate the effects of Artificial Tear Preparations (ATP) with three different ingredients on contrast sensitivity in patients with dry eye syndrome. Contrast sensitivity measurements were obtained before and 5, 15, 30, 60, and 90 minutes after administering three different ATPs, containing dextran 70, hydroxypropyl methylcellulose (ATP-1), polyvinyl alcohol-povidone (ATP-2) and carbomer (ATP-3) to one eye of 20 patients with dry eye syndrome, who had been divided to three groups. Contrast sensitivity measurements were obtained at 1.5, 3, 6, 12, and 18 spatial frequencies (cpd). Compared with the baseline measurements, ATP-1 provided a significant increase of 1.5 and 3 cpd at the 15th minute, 12 cpd at the 60th minute, and 18 cpd at the 30th minute, ATP-2 significantly increased contrast sensitivity compared with the baseline at the 15th, 30th, 60th, and 90th minute measurements, recorded as 1.5, 3, 12, and 18 cpd, and ATP-3 provided significant increases of 18 cpd at 60th and 90th minute measurements compared with the baseline. In conclusion, while ATP-2 increased the majority of contrast sensitivity measurements both at early, mid, and late terms, the ATP-1 and ATP-3 were found to be effective on mid-term and late-term contrast sensitivity measurements, respectively.
Comparison of Visual, Refractive and Aberration Measurements of INTACS versus Tricyclic ICL Lens Implantation; A Four-year Follow-up
Full text linkThis study was performed to evaluate the visual, refractive, and aberration measurement results of 2 implants, including Intacs Intracorneal Ring Segments (ICRS) and phakic Toric Implantable Collamer Lens (TICL), in patients with moderate Keratoconus (KCN). In this retrospective cross-sectional study, 30 patients with KCN with a mean age of 29.83 years were included in 2 groups, including the Intacs Intracorneal Ring Segments (ICRS) group and the phakic Toric Implantable Collamer Lens (TICL) group. Preoperative data as well as 6-month, 1-, 2-, 3- and 4-year follow-up data after the operation were collected and analyzed with the SPSS software (ver. 23.0, SPSS, Inc., Chicago, IL), using the paired t-test, independent t-test, repeated measures Analysis of Variance (ANOVA), and one-way ANOVA. This study included 30 patients with KCN with a mean age of 29.83 years and range of 25 to 35 years, including 17 males with a mean age of 30.11 years and 13 female with a mean age of 29.25 years. Except for preoperative Uncorrected Distance Visual Acuity (UCDVA), Spherical Equivalent (SE) and astigmatism, there was a significant difference between the 2 groups regarding other variables. The TICL group had a significantly better UCDVA and Best Corrected Distance Visual Acuity (BCDVA) in all post-operative follow-ups, and SE and astigmatism values were significantly lower in all post-operative follow-ups when compared with the ICRS group. There was a significant reduction in corneal and total coma as well as internal trefoil aberrations (P<0.01, P<0.01, and P=0.014, respectively) in the ICRS group, and TICL led to a significant reduction in internal trefoil aberration with P<0.03. Comparison of the 2 groups revealed a significant difference in corneal spherical (P<0.01) and total coma (P=0.02) aberrations and no significant differences in other HOA. Both ICRS and TICL are useful in patients with moderate KCN. However, TICL appears to have more stable and predictable vision results.
Consanguineous Marriage as a Risk Factor for Developing Keratoconus
Full text linkHeredity plays an important role in keratoconus (KC). Consanguineous marriage (CM) can affect the transmission of recessively inherited conditions. We aimed to investigate the role of consanguineous marriage in the development of KC. This study included two groups: the first group comprised 415 patients who underwent surgery for KC for the first time at Khalili University Hospital (Shiraz, Iran), between 2010 and 2014; the second group comprised 415 healthy individuals who served as age- and sex-matched controls for the patient group. All study subjects were from the Fars province in Iran. CM type was evaluated by a standard checklist in both groups. The mean inbreeding coefficient (α) was evaluated and compared between the two groups. The percentage of parental first-cousin marriages was 35.4% in the patient group and 18.3% in the control group. The mean inbreeding coefficient (α) was 0.0291 in the patient group and 0.0135 in the control group. Patients with KC had a significantly higher mean inbreeding coefficient (α) than controls (T = 8, df = 828, P < 0.001). Our study suggests that CM can play a role in the pathogenesis of KC. As this disease is among the most frequent ocular disorders in our country, CM should be considered by health care systems within their screening programs
Short-Term Results of Sutureless Scleral Tunnel Trabeculectomy Using Adjunctive Topical Bevacizumab
Full text linkThis study was performed to assess the short-term effect of sutureless scleral tunnel trabeculectomy procedure with and without topical bevacizumab. Thirty patients with Primary Open-Angle Glaucoma (POAG) were enrolled and randomly divided to two groups. Patients in the first group (15 patients) underwent sutureless trabeculectomy without topical bevacizumab and patients in the second group (15 patients) underwent sutureless trabeculectomy with 1.25 mg of topical bevacizumab. Intraocular Pressure (IOP) of both groups was measured by an expert ophthalmologist, without awareness of the patient’s study group before the operation and six months post-operatively. Out of 30 patients in this study, six females (40%) and nine males (60%) underwent the sutureless trabeculectomy procedure (group A) as well as seven females (46.7%) and eight males (53.3%) underwent sutureless trabeculectomy with topical bevacizumab (group B). The mean age of the patients was not significantly different between the two groups (P = 0.91). A statistically significant difference in time variation of IOP was found between the two groups (P < 0.001). Mean IOP was 18.4 ± 4.35 mmHg in the sutureless group without bevacizumab and 11.73 ± 2.12 mmHg in the sutureless group with bevacizumab, six months post-surgically. No statistical significant differences were found in the baseline IOP between the two groups (P = 0.28). However, IOP changed significantly in group A and B from baseline to six months post-operatively (P = 0.004 and P < 0.001 respectively). According to the current findings, the sutureless trabeculectomy procedure is an effective surgical method for reduction of IOP. Addition of a single dose of 1.25 mg topical bevacizumab was more effective in reduction of IOP compared to sutureless trabeculectomy alone.
Reoperation in Horizontal Strabismus and its Related Risk Factors
Full text linkThis study was performed to determine the surgical outcomes and the related risk factors of second operation in patients with residual horizontal deviations. In this interventional case series study, a total of 119 patients with a history of reoperation were included (39 exotropia and 80 esotropia). Cases with consecutive strabismus, muscular palsy, systemic disease, lack of ocular fixation, and those, who had vertical deviation and Dissociated Vertical Deviation (DVD)>5 Prism Diopters (pd) were excluded. Medial Rectus (MR) resection in residual Exotropia (XT) and Lateral Rectus (LR) resection in residual Esotropia (ET) were performed. Unilateral or bilateral operations were considered if the preoperative residual deviation was < 20 pd or > 20 pd, respectively. Success of the reoperation was considered if the postoperative angle of deviation was ≤ 10 pd. Unilateral and bilateral MR resection was performed in 26% and 74% of patients with XT, respectively, with greater dose response in unilateral cases (2.8 versus 2.6 mm/pd). Successful surgical outcomes were observed in 94.9% of patients with XT. Unilateral and bilateral LR resection was also performed in patients with residual ET, each in 50% of patients. Unilateral cases showed greater dose-response compared to bilateral ones (2.6 versus 2 mm/pd) and successful surgical outcomes were observed in 83.8% of patients with ET. No variable was found as a risk factor of reoperation in both groups. In conclusion, both LR and MR resection are easy and predictable surgical approaches with high success rate in patients with residual ET and XT. Generally, MR resection is more effective than LR resection. Unilateral operation is less recommended in the residual exotropic group, due to its lower success compared to the bilateral operation. Unfortunately, none of the mentioned variables were found to be the risk factor of reoperation in the sampled patients.
Intraocular Hemorrhage due to use of Sildenafil in a Patient with Diabetes
Full text linkSildenafil is one of the most commonly used drugs for sexual dysfunction or to increase libido, and it regulates endothelial nitric oxide synthase enzyme via selective phosphodiesterase-V inhibition. Sildenafil can be easily obtained without a medical indication or prescription yet it is not considered as a completely safe medication. Hemoptysis and hemorrhagic stroke are some important adverse effects of sildenafil. The case of the current report was a 67-year-old diabetic patient with simultaneous anterior and posterior segment hemorrhage after the use of 100 mg sildenafil citrate. Anterior chamber clearance and pars plana vitrectomy were performed for the patient because the hyphema and vitreous hemorrhage did not resolve during the follow-up period. There are very limited data available in the literature suggesting an increase in the risk of hyphema or vitreous hemorrhage due to the use of sildenafil. This is the first report that reveals the bleeding effect of sildenafil use in a patient with type 2 diabetes
Accelerated versus Conventional Corneal Collagen Cross-Linking for Progressive Keratoconus
Full text linkWe aimed to compare the effect of accelerated and conventional corneal collagen cross-linking (CXL) on visual, refractive, and topographic parameters in patients with progressive keratoconus. Between December 2014 and February 2016, at Imam Khomeini Hospital, Ahvaz Jundishapur University of Medical Sciences, Iran, we compared 37 eyes of 21 patients treated by conventional CXL (CCXL; 3 mW/cm2 in 30 minutes) with 34 eyes of 18 patients treated by accelerated CXL (ACXL; 18 mW/cm2 in 5 minutes) based on generalizing estimation equation analysis in terms of corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), corneal endothelial cell indices, and topographic parameters before and at 3, 6 and 12 months after the operation. The mean UDVA and spherical equivalent changes were similar in the two groups, but an improvement in CDVA was only observed in the CCXL group (P = 0.003). Keratometry (minimum and maximum) was significantly decreased in the CCXL group (P = 0.043 and P = 0.008, respectively). Indices of keratoconus progression—surface asymmetry index (SAI), keratoconus prediction index (KPI), and keratoconus index (KCI)—were significantly lower in the CCXL group than in the ACXL group (P = 0.002, P < 0.001, and P < 0.001, respectively). The thinnest corneal thickness (TCT) was not significantly different between the two groups (P = 0.15). The reduction of corneal endothelial cell density was also similar between the two groups; however, polymorphism and polymegethism were significantly lower in the ACXL group than in the CCXL group. In conclusion, we showed that although ACXL at 18 mW/cm2 slowed keratoconus progression safely during a 1-year follow-up, CCXL at 3 mW/cm2 may be superior in the prevention of keratoconus progression
Micropulse Laser for Persistent Sub-Retinal Fluid in a Patient Previously Treated for Rhegmatogenous Retinal Detachment
Full text linkThe purpose of this study was to report the resolution of persistent Sub-Retinal Fluid (SRF) induced by subthreshold micropulse laser treatment in a patient, formerly treated for rhegmatogenous retinal detachment by retinal pneumopexy. The case was a 41-year-old male, who initially presented macula-splitting rhegmatogenous retinal detachment and corrected distance visual acuity of 20/40 in his left eye. He was treated by retinal pneumopexy and laser retinopexy. Retina was flattened and vision improved to 20/30. However, the subretinal fluid (SRF) under the fovea was persistently observed on repeated retinal exams. Fourteen months after the initial pneumopexy, subthreshold micropulse laser was applied to cover the entire area of the SRF. The improvement started two weeks afterwards and the SRF completely resolved within four months after the application of micropulse laser. Corrected distance visual acuity improved from 20/30 to 20/20, accompanied by marked improvement in patient’s complaints on visual blurriness. The patient was followed up for three years and no recurrence of SRF was noted. The findings of this report indicate that subthreshold micropulse laser may serve as a therapeutic option for persistent SRF, which may be observed after successful retinal detachment repair