Cutting Edge: Corneal Stromal Lenticule Implantation (Corneal Stromal Augmentation) for Ectatic Disorders

ABSTRACT

The ectatic disease of the cornea poses a significant challenge for ophthalmologists because commonly used treatments to improve visual acuity, such as spectacles and contact lenses, may not be effective, especially in advanced stages. In addition, the preferred surgical management, corneal transplantation, has various issues related to tissue availability, the steep learning curve, and postoperative complications such as tissue stability and half-life. Ongoing research for an alternative to keratoplasty has suggested various methods, such as corneal crosslinking, which can improve visual function when combined with other techniques. Early reports have become available on the feasibility and safety of different strategies for corneal stromal augmentation, both with and without corneal crosslinking, and their favorable clinical outcomes, including visual and keratometry improvements. Here, we explore the cutting-edge advancements in stromal lenticule implantation, encompassing different facets of the procedure.

Long-Term Clinical Outcomes of Keratolimbal Allograft Alone or in Combination With Keratoplasty in Chronic and Delayed-Onset Mustard Gas Keratopathy

PURPOSE

The purpose of this study was to investigate the long-term clinical outcome of keratolimbal allograft (KLAL) alone or in combination with keratoplasty, in the management of patients with chronic and delayed-onset mustard gas keratopathy (MGK).

METHODS

Patients who had KLAL for MGK with or without corneal transplantation between 2002 and 2016 were recalled to be enrolled in this retrospective interventional case series. The primary outcome was the success rate of the KLAL demonstrated by Kaplan-Meier cumulative survival analysis. The secondary outcomes were postoperative BCVA and the need for further surgery.

RESULTS

A total of 108 eyes of 68 patients with MGK underwent KLAL. All patients were male with an average age of 54 ± 6 years with an average follow-up duration of 81.9 ± 38.4 months. Sectoral KLAL alone was performed in 62 eyes (57.4%), combined with lamellar keratoplasty (LKP) in 40 eyes (37%) and combined with penetrating keratoplasty in 6 eyes (5.6%). The cumulative probability of success was 75% within the follow-up duration. The mean duration of successful KLAL survival was 80.6 ± 38 months. 88.1% of these eyes needed only 1 operation to stabilize the ocular surface. Average BCVA did not improve significantly after KLAL alone, except in those accompanied by keratoplasty. KLAL combined with LKP achieved the superior clinical outcome compared with KLAL alone. Infectious keratitis occurred in 6 eyes (5.5%). No adverse event due to postoperative systemic immunosuppression was observed.

CONCLUSIONS

KLAL alone or combined with LKP is effective, durable, and visually acceptable in the reconstruction of ocular surface in patients with limbal stem cell deficiency secondary to MGK.

A Modified Formula for Intraocular Lens Power Calculation Based on Aphakic Refraction in a Pediatric Population

Purpose

To investigate and optimize the accuracy of aphakic refraction (AR) techniques for secondary intraocular lens (IOL) power calculation in aphakic children.

Methods

Thirty-three aphakic eyes of 18 patients who were candidates for secondary IOL implantation were enrolled in the present study. Axial length (AL) measured by optical biometry was used in the biometric formula (SRK-T, Holladay II, and Hoffer-Q). AR and spherical equivalent (SE) were used in two AR-based formulas (Ianchulev, Leccissotti). True power was calculated based on postoperative SE at three months' follow-up.

Results

Regarding the postoperative SE, 13 (40%) eyes were within ± 1.00 diopters (D) and 22 (66%) were within ± 2.00 D. Median absolute error (MedAE) was predicted to be 4.4 and 7.3 D with the use of Ianchulev and Leccissotti formulas, respectively. The corresponding value was 0.8 D with the biometric formula. All eyes were deemed to have myopic refraction when using the AR-based formulas except one eye with the Ianchulev formula. The coefficient of our modified formula was 1.7 instead of 2.01 in the Ianchulev formula. MedAE with the use of new formulae was 0.5 D and was comparable with the true IOL power (P = 0.22).

Conclusion

Both Ianchulev and Leccissotti formulas resulted in a significant myopic surprise in aphakic children aged between 4.5 and 14 years. The modified formula proved to determine a more accurate SE that is comparable with biometric formulas.

Femtosecond Laser-assisted Allogenic Additive Stromal Keratoplasty With or Without Excimer Laser Donor Keratomileusis for Management of Keratoconus

We describe a modified allogenic intrastromal lenticule implantation technique for management of keratoconus (KCN). Patients with advanced KCN already scheduled for corneal transplantation were enrolled. An allogenic corneal lenticule was implanted inside a stromal pocket created by femtosecond laser. In three cases, the estimated refractive error of the recipient eyes was corrected on the donor lenticules using an Excimer laser. All operated eyes underwent corneal crosslinking at the time of surgery. This method was named “Femtosecond Laser-assisted Allogenic Stromal Keratoplasty Without and With Excimer Laser-assisted Donor Keratomileusis”; briefly called FASK and FASK Plus EDK, respectively. Two out of five patients were satisfied with the results. There was a decrease in the average simulated keratometric values as well as myopia when FASK Plus EDK was performed. Increased corneal thickness was achieved in all cases. Graft edema gradually decreased over weeks but interface wrinkling and lenticule folds in the visual axis remained as a problem during follow-up period. No other complications were encountered.

Secondary Piggyback Intraocular Lens for Management of Residual Ametropia after Cataract Surgery

Purpose

To investigate the indications, clinical outcomes, and complications of secondary piggyback intraocular lens (IOL) implantation for correcting residual refractive error after cataract surgery.

Methods

In this prospective interventional case series, patients who had residual refractive error after cataract surgery and were candidates for secondary piggyback IOL implantation between June 2015 and September 2018 were included. All eyes underwent secondary IOL implantation with the piggyback technique in the ciliary sulcus. The types of IOLs included Sulcoflex and three-piece foldable acrylic lenses. Patients were followed-up for at least one year.

Results

Eleven patients were included. Seven patients had hyperopic ametropia, and four patients had residual myopia after cataract surgery. The preoperative mean of absolute residual refractive error was 7.20 ± 7.92, which reached 0.42 ± 1.26 postoperatively (P< 0.001). The postoperative spherical equivalent was within ±1 diopter of target refraction in all patients. The average preoperative uncorrected distance visual acuity was 1.13 ± 0.35 LogMAR, which significantly improved to 0.41 ± 0.24 LogMAR postoperatively (P = 0.008). There were no intra- or postoperative complications during the 22.4 ± 9.5 months of follow-up.

Conclusion

Secondary piggyback IOL implantation is an effective and safe technique for the correction of residual ametropia following cataract surgery. Three-piece IOLs can be safely placed as secondary piggyback IOLs in situations where specifically designed IOLs are not available.

Aloe Vera Gel-derived Eye Drops for Alkaline Corneal Injury in a Rabbit Model

Purpose

To investigate the efficacy of topical Aloe Vera (AV) gel-derived eye drops on the healing of alkali-burned corneas in rabbits.

Methods

Thirty alkali-burned corneas of 30 New Zealand albino rabbits were categorized into three groups: AV treatment group that received AV gel-derived eye drops four times a day; medical therapy (MT) group that received conventional treatment; and the control group. Clinical examinations together with digital imaging of the corneas were performed on days 0, 1, 2, 4, and 7. The area of the corneal epithelial defect (CED) was measured using ImageJ software. After euthanizing the rabbits, the affected corneas were evaluated by histopathological examination. Finally, the clinical and histopathological results were compared among the groups.

Results

The CED area on days 2 and 7 was significantly less in the AV group than that in the MT group (P = 0.007 and P = 0.024, respectively) and the control group (P = 0.003 and P = 0.037, respectively). None of the cases developed hypersensitivity reactions, limbal ischemia, descemetocele, or corneal perforation during the study period. Based on histopathology, the AV group had notably less keratocyte loss than the MT group (P = 0.001) and the control group (P = 0.022). The inflammatory response after the alkali burn was higher in the AV group than that in the controls (P = 0.028).

Conclusion

Short-term topical AV treatment was effective in healing alkali-burned corneas and hastened corneal re-epithelialization as compared to MT; however, AV gel-derived eye drops did not reduce the inflammatory response.

Traumatic Wound Dehiscence following Corneal Transplantation

PURPOSE

To investigate the incidence, mechanisms, characteristics, and visual outcomes of traumatic wound dehiscence following keratoplasty.

METHODS

Medical records of 32 consecutive patients with traumatic globe rupture following keratoplasty who had been treated at our center from 2001 to 2009 were retrospectively reviewed.

RESULTS

The study population consisted of 32 eyes of 32 patients including 25 men and 7 women with history of corneal transplantation who had sustained eye trauma leading to globe rupture. Mean patient age was 38.1 (range, 8 to 87) years and median interval between keratoplasty and the traumatic event was 9 months (range, 30 days to 20 years). Associated anterior segment findings included iris prolapse in 71.9%, lens extrusion in 34.4%, and hyphema in 40.6% of eyes. Posterior segment complications included vitreous prolapse (56%), vitreous hemorrhage (28%) and retinal detachment (18%). Eyes which had undergone deep anterior lamellar keratoplasty (DALK; 5 cases, 15.6%) tended to have less severe presentation and better final visual acuity. There was no correlation between the time interval from keratoplasty to the traumatic event, and final visual outcomes.

CONCLUSION

The host-graft interface demonstrates decreased stability long after surgery and the visual prognosis of traumatic wound dehiscence is poor in many cases. An intact Descemet's membrane in DALK may mitigate the severity of ocular injuries, but even in these cases, the visual outcome of globe rupture is not good and prevention of ocular trauma should be emphasized to all patients undergoing any kind of keratoplasty.

Aspergillus flavus keratitis after deep anterior lamellar keratoplasty

PURPOSE

To report the clinical, microbiologic, confocal scan and histopathologic features of Aspergillus flavus keratitis which developed immediately after deep anterior lamellar keratoplasty (DALK).

CASE REPORT

A 28-year-old woman underwent DALK using the big-bubble technique for keratoconus. The operation was uneventful, yielding a bare Descemet's membrane (DM) followed by transplantation of a corneal graft devoid of DM and endothelium. Four days after keratoplasty, mild infiltrates were noticed in the inferonasal margin of the graft, which rapidly progressed to involve the adjacent recipient cornea. Confocal scan findings suggested filamentous fungal keratitis, leading to initiation of topical and systemic antifungal medications followed by immediate replacement of the graft. Histopathologic examination disclosed keratitis caused by a filamentous fungus, which was determined by microbiologic cultures to be Aspergillus flavus. Early diagnosis and appropriate management resulted in complete recovery from this potentially devastating infection.

CONCLUSION

Aspergillus Flavus can cause graft ulcers immediately after DALK. Confocal scan proved to be a valuable tool for early diagnosis and prompt intervention to control this otherwise devastating infection.

Immunologic corneal graft rejection after administration of topical latanoprost: a report of two patients

PURPOSE

To report endothelial corneal graft rejection after administration of topical latanoprost eye drops.

CASE REPORT

Two eyes of two patients with a history of multiple intraocular procedures prior to penetrating keratoplasty developed endothelial graft rejection one month after administration of topical latanoprost. Cystoid macular edema developed simultaneously in one patient.

CONCLUSION

Latanoprost may trigger endothelial graft rejection in susceptible eyes.

The effect of mitomycin-C on corneal endothelial cells after photorefractive keratectomy

PURPOSE

To evaluate short-term changes in central corneal endothelial cell density and morphology after photorefractive keratectomy (PRK) with mitomycin-C (MMC) 0.02% in patients with moderate myopia.

METHODS

In this prospective interventional case series, patients with moderate myopia (spherical equivalent refractive error from -4.0 to -8.0 D) underwent PRK with a single intraoperative application of MMC 0.02% for 40 seconds. Specular microscopy was performed preoperatively and repeated 6 months after surgery to determine changes in central corneal endothelial cell density (ECD), mean cell area (MCA) and coefficient of variation in cell size (CV).

RESULTS

Overall, 42 eyes of 21 participants with mean age of 26.2±6.3 years underwent surgery. Mean preoperative spherical equivalent refractive error was -5.2±1.2 D which was reduced to -0.4±0.5 D postoperatively (P < 0.001). Mean ECD was reduced insignificantly from 2,920±363 cells/mm(2) preoperatively to 2,802±339 cells/mm(2) postoperatively (P = 0.59). Similarly, there was no significant change in MCA or CV at six months (P = 0.76 and 0.52, respectively).

CONCLUSION

Application of MMC 0.02% for 40 seconds during PRK in patients with moderate myopia did not significantly affect central corneal endothelial cell density and morphology after a 6 month follow up period.

Aspheric versus Spherical Posterior Chamber Intraocular Lenses

PURPOSE

To compare spherical aberration and contrast sensitivity function following implantation of four different foldable posterior chamber intraocular lenses (IOLs), namely Sensar, Akreos AO, Tecnis, and AcrySof IQ.

METHODS

In this randomized clinical trial, 68 eyes of 68 patients with senile cataracts underwent phacoemulsification and IOL implantation with Sensar (n=17), Akreos AO (n=17), Tecnis (n=17), or AcrySof IQ (n=17). Uncorrected visual acuity (UCVA) and best spectacle-corrected visual acuity (BSCVA), spherical aberration and contrast sensitivity function (CSF) were compared among the study groups, 3 months after surgery.

RESULTS

There was no significant difference between the study groups in terms of age (P = 0.21). Mean postoperative BSCVA with Sensar, Akreos AO, Tecnis, and AcrySof IQ was 0.15±0.10, 0.12±0.9, 0.08±0.08, and 0.08±0.07 logMAR, respectively (P=0.08). Spherical aberration measured over a 4 mm pupil was significantly higher with Sensar and Akreos AO than the two other IOLs. The difference between Tecnis and AcrySof IQ was significantly in favor of the former IOL. Over a 6 mm pupil, spherical aberrations were comparable with Sensar and Akreos AO, furthermore spherical aberration was also comparable among eyes implanted with Akreos AO, AcrySof IQ, and Tecnis. Sensar yielded significantly inferior results as compared to Acrysof IQ and Tecnis. CSF with Sensar was inferior to the three aspheric IOLs at the majority of spatial frequencies. Tecnis yielded significantly better mesopic CSF at 1.5 and 3 cycles per degree spatial frequencies.

CONCLUSION

Tecnis and AcrySof IQ provided significantly better visual function as compared to Sensar and Akreos AO, especially with smaller pupil size. However, this difference diminished with increasing pupil size.

Outcomes of penetrating keratoplasty for macular corneal dystrophy

PURPOSE

To report the outcomes of penetrating keratoplasty (PKP) in patients with macular corneal dystrophy (MCD).

METHODS

This retrospective case series includes consecutive patients with MCD who underwent PKP from 1986 to 2006 with at least 6 months' follow-up. Main outcome measures included best spectacle-corrected visual acuity (BSCVA), postoperative astigmatism and graft survival.

RESULTS

Sixty-two eyes of 39 patients with mean age of 34.0±10.5 (range 13-58) years at the time of keratoplasty were included for analysis. After a mean follow-up period of 52.0±47.3 (range 6-190) months, BSCVA improved from 1.4±0.4 logMAR (4/100) preoperatively to 0.2±0.3 logMAR (20/32) at final follow-up (P<0.001).Mean postoperative BSCVA was 0.15±0.40 logMAR in patients (36 eyes) aged less than 35 years at the time of surgery as compared to 0.26±0.25 logMAR in subjects (26 eyes) older than 35 years (P=0.005). Final astigmatism was comparable with different suturing techniques including separate, continuous, and combined sutures (P=0.9). All grafts were clear at final follow-up except a single case of MCD with visually insignificant recurrence.Episodes of immunologic graft rejection occurred in 12 eyes (19.4%) but none led to graft failure.

CONCLUSION

PKP for MCD entails favorable outcomes in terms of graft survival and visual improvement. Final visual acuity seems to be better when transplantation is performed before the age of 35 years.

Lensectomy and PCIOL Implantation with versus without Posterior Capsulotomy and Anterior Vitrectomy for Pediatric Cataracts

PURPOSE

To compare the visual outcomes and complications of lensectomy and posterior chamber intraocular lens (PCIOL) implantation with or without posterior capsulotomy and anterior vitrectomy in older subjects with pediatric cataracts.

METHODS

Seventeen eyes of 12 children aged 10 to 15 years with congenital or developmental cataracts were randomly divided to two groups. Lensectomy and PCIOL (Alcon Acrysof MA60 AC) implantation was performed with (8 eyes) or without (9 eyes) posterior capsulotomy and anterior vitrectomy.

RESULTS

Mean age at the time of surgery was 12.3±1.5 (range 10-15) years and mean follow-up period was 18.7±11.2 (range 6-36) months. Posterior capsule opacification developed in three eyes in the non-vitrectomy group; however, media opacification was mild and capsulotomy was not required in any case. All eyes in the vitrectomy group had a clear visual axis at final follow-up (P=0.2). No significant difference was observed between the two groups in term of visual acuity (P=0.3) or complications.

CONCLUSION

Although posterior capsulotomy and anterior vitrectomy seems to be safe in pediatric cataract surgery, it may not be necessary as a routine procedure in older children.

Visual Outcomes of Two Aspheric PCIOLs: Tecnis Z9000 versus Akreos AO

PURPOSE

TO COMPARE SPHERICAL ABERRATION AND CONTRAST SENSITIVITY WITH TWO DIFFERENT TYPES OF ASPHERIC POSTERIOR CHAMBER INTRAOCULAR LENSES (PCIOLS): Tecnis Z9000 versus Akreos AO.

METHODS

Thirty-four eyes of 34 patients undergoing phacoemulsification for senile cataracts were randomly assigned to implantation of Tecnis Z9000 or Akreos AO PCIOLs. Outcome measures included best-corrected visual acuity (BCVA), spherical aberration (SA) with 4 and 6 mm pupil diameters and contrast sensitivity under photopic and mesopic conditions at spatial frequencies of 1, 2, 5, 10 and 20 cycles per degree (cpd) three months postoperatively.

RESULTS

Mean BCVA was 0.08±0.08 logMAR in the Tecnis Z9000 group and 0.11±0.09 logMAR in the Akreos AO group (P=0.33). SA was less with Tecnis than Akreos AO with 4 and 6 mm pupil diameter (0.14±0.10 μm vs 0.28±0.09μm, P< 0.001 and 0.30±0.18μm vs 0.33±0.08 μm, P=0.4, respectively). Contrast sensitivity was significantly higher in the Tecnis Z9000 group at 1, 2, 5 and 10 cpd under photopic and at 1, 2 and 10 cpd under mesopic conditions.

CONCLUSION

Tecnis Z9000 IOL seems to entail better visual outcomes in terms of spherical aberration and contrast sensitivity as compared to Akreos AO.

Bilateral Bacterial Keratitis in Three Patients Following Photorefractive Keratectomy

PURPOSE

To report clinical manifestations and the bacteriologic profiles of three patients with bilateral bacterial keratitis following photorefractive keratectomy (PRK).

METHODS

Photorefractive keratectomy was performed for mild to moderate myopia or compound myopic astigmatism. Bandage contact lenses were fitted at the conclusion of each surgery. Bilateral infectious keratitis was diagnosed within 3 days after surgery. Smear and culture were obtained in all three cases. Patients were treated with topical fortified antibiotics (cefazolin and gentamicin).

RESULTS

All patients presented with severe bilateral ocular pain, photophobia, purulent discharge, and dense corneal infiltration. Causative organisms were Staphylococcus aureus (n = 2) and Streptococcus pneumoniae (n = 1). Ulcers were controlled with aggressive medical therapy in five eyes; however, tectonic penetrating keratoplasty was required in one eye.

CONCLUSIONS

Uncontrolled blepharitis and bandage contact lens use appears to play a role in the development of bacterial keratitis after PRK. Avoidance of simultaneous bilateral surgery in patients with risk factors for bacterial keratitis, preoperative control of blepharitis, and good contact lens hygiene is suggested.

Outcomes of phacoemulsification and in-the-bag intraocular lens implantation in Fuchs' heterochromic iridocyclitis

PURPOSE

To evaluate the visual outcomes and complications of phacoemulsification (PE) and posterior chamber intraocular lens implantation, (PC IOL) in patients with Fuchs heterochromic iridocyclitis (FHIC).

SETTING

Private clinic and an academic hospital.

METHODS

In this noncomparative interventional case series, existing data for 41 eyes of 40 consecutive patients clinically diagnosed with FHIC and cataract were studied retrospectively. Scleral tunnel PE and in-the-bag IOL implantation were performed in all cases. Preoperative and postoperative visual acuities and intraoperative and postoperative complications were evaluated.

RESULTS

Twenty-four male and 16 female patients aged 12 years to 70 (SD) (mean 35 +/- 12 years) were operated on and followed for 17.8 +/- 8.7 months. Preoperatively, best corrected visual acuity (BCVA) was less than 20/40 in all patients, which improved to 20/40 or better after surgery. Twenty-two eyes (53.6%) achieved BCVA of 20/20. The major cause of postoperative visual acuity less than 20/20 was vitreous haze. There were no major intraoperative complications. Postoperatively, mild anterior chamber fibrin reaction occurred in 4 patients (9.7%), IOL deposits occurred in 11 eyes (26.8%), and decentration was observed in 1 eye. During follow-up, 6 eyes (14.6%) developed posterior capsule opacification requiring a neodymium:YAG (Nd:YAG) laser capsulotomy. There was 1 case of clinical cystoid macular edema that resolved with medication. There were no cases of posterior synechias, postoperative glaucoma, or retinal detachment.

CONCLUSION

Phacoemulsification with PC IOL implantation is a safe procedure with good visual outcomes in patients with FHIC and cataract.

Cataract surgery and intraocular lens implantation in anterior megalophthalmos

Six eyes of 4 patients with anterior megalophthalmos, 2 men and 2 women ranging in age from 32 to 47 years, had extracapsular cataract extraction or phacoemulsification and standard posterior chamber intraocular lens implantation. All had a family history of anterior megalophthalmos. Follow-up was from 6 to 30 months. All patients had a preoperative visual acuity of worse than 20/60, which improved to 20/20 in 5 eyes. Zonular dehiscence was observed during surgery in 3 cases, leading to vitreous loss in 1 case that developed a retinal detachment after 3 months.