Elias Jarade

New formula for calculating intraocular lens power after laser in situ keratomileusis

Purpose: To assess the validity and accuracy of a proposed formula for keratometry (K) readings after laser in situ keratomileusis (LASIK). Setting: The Eye Center and the Eye Foundation for Research, Riyadh, Saudi Arabia. Method: This studied comprised 34 eyes that had LASIK surgery. Refraction and an automated K‐reading (auto‐K) were performed preoperatively. Refraction, auto‐K, and K‐reading assessment by the clinical history method and the proposed formula were performed 4 to 12 weeks postoperatively. The proposed formula is Kpostop = Kpreop – [(Nc – 1) × (Ra‐postop – Ra‐preop)/(Ra‐postop × Ra‐preop)], where Kpostop is the K‐reading after LASIK, Kpreop is the K‐reading before LASIK, Nc is the index of refraction of the cornea (1.376), Ra‐postop is the radius of curvature of the anterior corneal surface after LASIK, and Ra‐preop is the radius of curvature of the anterior corneal surface before LASIK. Results: Twenty patients (10 men, 10 women) were included in the study. The mean age of the patients was 30.58 years ± 17.68 (SD) (range 18 to 44 years). Preoperatively, the mean spherical equivalent (SE) was –4.99 ± 2.82 diopters (D) (range –1.12 to –15.00 D), the mean Ra was 7.76 ± 0.32 mm (range 7.33 to 8.50 mm), and the mean auto‐K reading was 43.45 ± 1.73 D (range 39.62 to 46.00 D). Postoperatively, the mean SE was +0.02 ± 0.63 D (range –2.75 to +1.00 D), the mean Ra was 8.63 ± 0.53 mm (range 7.80 to 9.92 mm), and the mean K‐reading assessed by auto‐K, clinical history method, and the proposed formula was 39.17 ± 2.35 D (range 34.00 to 43.25 D), 38.79 ± 2.52 D (range 33.1 to 42.78 D), and 38.69 ± 2.51 D (range 33.1 to 43.0 D), respectively. The results obtained by the proposed formula were similar to those obtained by the clinical history method (P = .098). Auto‐K readings significantly overestimated the K‐values (P<.0001) when compared to the proposed formula and clinical history method. Conclusion: The proposed formula was simple, objective, not dependent on refraction, and as accurate as the clinical history method in determining K‐readings after LASIK.

Intraocular lens power calculation following LASIK : Determination of the new effective index of refraction

PURPOSE To determine the new corneal effective index of refraction (rN) following LASIK to be used for accurate keratometry reading (K-reading). METHODS A total of 332 eyes that underwent myopic LASIK were divided into two groups (group A [n = 137] and group B [n = 1951). In each group, patients were divided into four subgroups according to the amount of spherical equivalent refraction of myopic LASIK ablation (subgroup 1 [< -4.0 D], subgroup 2 [-4.0 to < -8.0 D], subgroup 3 [-8.0 to -12.0 D], and subgroup 4 [> -12.0 D]). In each subgroup of group A, K-reading was measured by the clinical history method and the new corneal effective index (rN) was determined using paraxial formula: (K-reading = (rN-1)/Ra), where Ra is the radius of curvature of the anterior corneal surface. In group B, the anterior radius of curvature of the cornea was determined by automated K-reading, and K-reading was measured in each subgroup using the new effective index in paraxial formula, clinical history method, and automated K-reading. RESULTS In group A, the new effective index of refraction was 1.3355, 1.3286, 1.3237, and 1.3172 in the four subgroups, respectively. In group B, the mean K-reading measurements using rN in paraxial formula, clinical history method, and automated K-reading were: 40.33 +/- 1.68 D, 40.33 +/- 1.67 D, and 40.54 +/- 1.69 D, respectively, in subgroup 1; 37.96 +/- 1.26 D, 38.03 +/- 1.38 D, and 38.98 +/- 1.28 D, respectively, in subgroup 2; 35.77 +/- 1.75 D, 35.84 +/- 1.85 D, and 37.29 +/- 1.83 D, respectively, in subgroup 3; and 34.03 +/- 1.49 D, 34.15 +/- 1.84 D, and 36.21 +/- 1.59 D, respectively, in subgroup 4. In all subgroups of group B, the results of K-reading obtained using the new effective index of refraction were statistically similar to the results obtained by clinical history method (P > .05). Automated K-reading statistically overestimated the K-reading values in subgroups 2, 3, and 4 of group B (P < .001). CONCLUSIONS The use of the new corneal effective index of refraction allows for an accurate derivation of K-reading from the anterior radius of curvature.

Indolent corneal ulcers in a patient with congenital insensitivity to pain with anhidrosis: a case report and literature review.

Purpose To report a case of bilateral corneal neurotrophic ulcer in patient with congenital insensitivity to pain with anhidrosis (CIPA) and review the literature. Case Report A 6 year-old boy presented with bilateral central corneal sterile ulcer, decreased corneal sensitivity, moderately altered corneal reflex and normal tearing response. History taken, systemic evaluation and medical chart review were undertaken. Discussion Fifty-two cases of CIPA have been reported worldwide. Fourteen cases had corneal involvement. The clinical picture of our patient is characteristic of CIPA. Conclusions Congenital insensitivity to pain with anhidrosis may present as neurotrophic corneal ulcer. We report herewith, this vision threatening corneal congenital abnormality. Early diagnosis and prompt treatment are mandatory to prevent corneal complications such as scarring and perforation.

Intraocular pressure measurement after hyperopic and myopic LASIK.

PURPOSE To assess the effects of hyperopic and myopic laser in situ keratomileusis (LASIK) on the intraocular pressure (IOP) measurement by Goldmann applanation tonometry. METHODS Intraocular pressure was measured by Goldmann applanation tonometry pre- and postoperatively in 48 hyperopic eyes (26 patients) and 56 myopic eyes (28 patients). RESULTS The mean preoperative spherical equivalent refraction was +3.97 +/- 2.48 diopters (D) in the hyperopic group and -6.73 +/- 4.79 D in the myopic group. Attempted correction was equivalent to preoperative refraction in each group. Mean preoperative IOP was 14.22 +/- 2.56 mmHg and 13.70 +/- 2.09 mmHg in the hyperopic and myopic groups, respectively. Following LASIK, the mean IOP was 11.85 +/- 2.52 mmHg and 11.38 +/- 3.08 mmHg in the hyperopic and myopic groups, respectively. CONCLUSIONS The IOP measurement was significantly reduced (P < .001) by 2.37-2.25 mmHg and 2.32 +/- 2.89 mmHg following hyperopic and myopic LASIK, respectively.

Presumed reactivation of herpes zoster ophthalmicus following laser in situ keratomileusis.

PURPOSE To report a case of herpes zoster ophthalmicus reactivation following laser in situ keratomileusis (LASIK) for myopia. METHODS A 54-year-old healthy male underwent uneventful bilateral LASIK for the correction of myopia and astigmatism (-5.75 -3.00 x 20 degrees right eye, -5.50 -3.00 x 170 degrees left eye). Two months following LASIK, an epithelial dendritic lesion appeared in the lower third of the corneal flap of the left eye with vesiculoulcerative lesions of the lateral side of the tip of the nose. RESULTS The patient was treated with topical and oral antiviral agents and had complete recovery of the lesions in 10 days. CONCLUSIONS Herpes zoster reactivation may occur following LASIK. Reactivation of herpes zoster in this case could have been coincidental, or secondary to LASIK and the subsequent use of topical corticosteroids following LASIK.

Safety and Visual Outcome of Visian Toric ICL Implantation after Corneal Collagen Cross-Linking in Keratoconus: Up to 2 Years of Follow-Up

Purpose. To evaluate the long-term safety and clinical outcome of phakic Visian toric implantable collamer lens (ICL) insertion after corneal collagen cross-linking (CXL) in progressive keratoconus. Methods. This was a retrospective study of 30 eyes (19 patients), with progressive keratoconus, who underwent sequential CXL followed by Visian toric ICL implantation after 6 months. Results. At baseline, 6 eyes had stage I, 14 eyes stage II, and 10 eyes stage III keratoconus graded by Amsler-Krumeich classification. At 6 months after CXL, only K (steep) and K (max) decreased significantly from baseline, with no change in visual acuity or refraction. Flattening in keratometric readings was stable thereafter. There was significant improvement in mean uncorrected distance visual acuity (1.57 ± 0.56 to 0.17 ± 0.06 logMAR, P < 0.001) and mean corrected distance visual acuity (0.17 ± 0.08 to 0.11 ± 0.05 logMAR, P < 0.001) at 12 months after ICL implantation that was maintained at the 2-year follow-up. Mean cylinder power and mean spherical equivalent (SE) also decreased significantly after ICL implantation. A small hyperopic shift in SE (+0.25 D) was observed at 2 years that did not alter visual outcomes. Conclusions. Visian toric ICL implantation following CXL is an effective option for improving visual acuity in patients with keratoconus up to 2 years.

Non-topography–guided PRK Combined With CXL for the Correction of Refractive Errors in Patients With Early Stage Keratoconus

PURPOSE To evaluate the safety and clinical outcome of combined non-topography-guided photorefractive keratectomy (PRK) and corneal collagen cross-linking (CXL) for the treatment of mild refractive errors in patients with early stage keratoconus. METHODS A retrospective, nonrandomized study of patients with early stage keratoconus (stage 1 or 2) who underwent simultaneous non-topography-guided PRK and CXL. All patients had at least 2 years of follow-up. Data were collected preoperatively and postoperatively at the 6-month, 1-year, and 2-year follow-up visit after combined non-topography-guided PRK and CXL. RESULTS Seventy-nine patients (140 eyes) were included in the study. Combined non-topography-guided PRK and CXL induced a significant improvement in both visual acuity and refraction. Uncorrected distance visual acuity significantly improved from 0.39 ± 0.22 logMAR before combined non-topography-guided PRK and CXL to 0.12 ± 0.14 logMAR at the last follow-up visit (P <.001) and corrected distance visual acuity remained stable (0.035 ± 0.062 logMAR preoperatively vs 0.036 ± 0.058 logMAR postoperatively, P =.79). The mean spherical equivalent decreased from -1.78 ± 1.43 to -0.42 ± 0.60 diopters (D) (P <.001), and the mean cylinder decreased from 1.47 ± 1.10 to 0.83 ± 0.55 D (P <.001). At the last follow-up visit mean keratometry flat was 43.30 ± 1.75 vs 45.62 ± 1.72 D preoperatively (P = .03) and mean keratometry steep was 44.39 ± 3.14 vs 46.53 ± 2.13 D preoperatively (P = .02). Mean central corneal thickness decreased from 501.74 ± 13.11 to 475.93 ± 12.25 µm following combined non-topography-guided PRK and CXL (P < .001). No intraoperative complications occurred. Four eyes developed mild haze that responded well to a short course of topical steroids. No eye developed infectious keratitis. CONCLUSIONS Combined non-topography-guided PRK and CXL is an effective and safe option for correcting mild refractive error and improving visual acuity in patients with early stable keratoconus.

Laser in situ keratomileusis in eyes with inactive herpetic keratitis.

PURPOSE To evaluate the safety and outcome of laser in situ keratomileusis in eyes with inactive herpetic keratitis. METHODS Prospective, interventional case series. In three eyes of three patients with inactive unilateral herpetic keratitis for a minimum period of 1 year, laser in situ keratomileusis was performed. Oral and topical acyclovir were prescribed perioperatively. No topical steroids were prescribed. RESULTS Preoperatively, all three eyes had corneal stromal scars with induced astigmatism in two eyes and central stromal scar in one eye with best-corrected visual acuity of 20/120, 20/25, and 20/50, respectively. Postoperatively, the three eyes achieved uncorrected visual acuity of 20/20, 20/20, and 20/50, respectively, with decreased corneal scar. None of the patients developed herpetic keratitis reactivation during a minimum follow-up of 6 months. CONCLUSION Laser in situ keratomileusis was safe and effective in the treatment of refractive errors and corneal scars in three eyes of three patients with inactive herpetic keratitis.

Visian toric ICL implantation after intracorneal ring segments implantation and corneal collagen crosslinking in keratoconus.

Purpose To evaluate the safety and clinical outcome of Visian toric implantable collamer lens (TICL) implantation for the treatment of residual refractive errors 6 months after sequential intracorneal ring segments (ICRS) and corneal collagen UVA crosslinking (CXL) in stable keratoconus. Methods This retrospective study examined the results of a 3-step ICRS-CXL-TICL in 11 eyes of 7 patients with moderate to severe keratoconus. The 2 procedures (ICRS-CXL) were performed sequentially at an interval of 4 weeks and TICL implantation was performed at least 6 months after CXL. Data were collected preoperatively, at the 6-month follow-up visit after sequential ICRS-CXL, and at the 6-month follow-up visit after TICL implantation. Results The ICRS-CXL induced a significant decrease in keratometry, increase in visual acuity, and decrease in refraction. At 6-month follow-up after ICRS-CXL, mean Kflat was 45.19 ± 3.98 D vs 48.51 ± 4.26 D preoperatively (p = 0.022) and mean Ksteep was 50.41 ± 4.32 D vs 54.24 ± 4.96 D preoperatively (p = 0.032). Uncorrected distance visual acuity (UCVA) significantly improved from 1.47 ± 0.38 logMAR before ICRS-CXL to 0.27 ± 0.20 logMAR 6 months after (p = 0.002). Corrected distance visual acuity (CDVA) significantly improved from 0.50 ± 0.22 logMAR to 0.29 ± 0.23 logMAR (p = 0.001). At 6 months post TICL implantation, UCVA improved significantly to 0.27 ± 0.20 logMAR and the CDVA was 0.19 ± 0.11 logMAR. No intraoperative or postoperative complications occurred. Conclusions Toric ICL implantation after sequential ICRS implantation and CXL is an effective and safe option for correcting high residual refractive error and improving visual acuity in patients with moderate to severe keratoconus.

Non-topography-guided photorefractive keratectomy for the correction of residual mild refractive errors after ICRS implantation and CXL in keratoconus.

PURPOSE To evaluate the safety and clinical outcomes of non-topography-guided photorefractive keratectomy (PRK) for the treatment of residual mild refractive errors 6 months after sequential intracorneal ring segment (ICRS) implantation and corneal collagen cross-linking (CXL) in stable keratoconus. METHODS This retrospective study included 17 eyes of 14 patients with mild to moderate keratoconus. The ICRS implantation and CXL were performed sequentially with a 4-week interval and non-topography-guided PRK was performed at least 6 months after CXL. Data were collected preoperatively and at the 6-month follow-up visits. RESULTS ICRS implantation and CXL induced a significant decrease in keratometry and refraction and an increase in visual acuity. At the 6-month follow-up after ICRS implantation and CXL, uncorrected and corrected distance visual acuity (UDVA and CDVA) significantly improved from 1.17 ± 0.38 and 0.44 ± 0.09 logMAR preoperatively to 0.45 ± 0.11 and 0.17 ± 0.08 logMAR (P = .001) postoperatively, respectively. The mean spherical error decreased from -5.45 ± 1.64 to -2.57 ± 1.15 D (P = .01) and the mean cylinder from 3.86 ± 1.15 to 2.13 ± 1.11 D (P = .01). At the 6-month follow-up after PRK, UDVA significantly improved to 0.18 ± 0.06 logMAR and CDVA was 0.15 ± 0.05 logMAR. The mean spherical error and mean cylinder significantly decreased to -1.10 ± 0.41 D (P = .02) and 0.98 ± 0.37 D (P = .046), respectively. No intraoperative or postoperative complications occurred. CONCLUSIONS At the 6-month follow-up, non-topography-guided PRK after ICRS implantation and CXL was found to be an effective and safe option for correcting residual refractive error and improving visual acuity in patients with moderate keratoconus.