1
|
Angelo L, Gokul Boptom A, McGhee C, Ziaei M. Corneal Crosslinking: Present and Future. Asia Pac J Ophthalmol (Phila) 2022; 11:441-452. [PMID: 36094381 DOI: 10.1097/apo.0000000000000557] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Accepted: 07/08/2022] [Indexed: 11/25/2022] Open
Abstract
Keratoconus is a progressive corneal thinning disorder that can lead to vision loss. In the last 2 decades, corneal crosslinking (CXL) has emerged as an effective method to halt the progression of keratoconus and reduce the number of patients requiring keratoplasty. The procedure has been adopted globally and has evolved to become a part of combination treatments to regularize the cornea and improve visual outcomes. CXL has even been extrapolated in managing other ocular pathologies such as progressive myopia, infectious keratitis, and bullous keratopathy. This review aims to summarize the current role of CXL in keratoconus and its alternative uses, and provide insights into future developments in this fast-developing field.
Collapse
Affiliation(s)
- Lize Angelo
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | | | | | | |
Collapse
|
2
|
Ashena Z, Doherty S, Gokul A, McGhee CNH, Ziaei M, Nanavaty MA. Flattening of Central, Paracentral, and Peripheral Cones After Non-accelerated and Accelerated Epithelium-off CXL in Keratoconus: A Multicenter Study. J Refract Surg 2022; 38:310-316. [PMID: 35536708 DOI: 10.3928/1081597x-20220404-02] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To assess the flattening of central, paracentral, and peripheral cones following non-accelerated (non-A-CXL) and accelerated (A-CXL) epithelium-off corneal cross-linking with 10 times higher intensity. METHODS In this multicenter study of 200 eyes (100 in each group), following 10 minutes of soak time with riboflavin 0.1%, continuous CXL was performed for 30 minutes (intensity: 3 mW/cm2, fluence: 5.4 J/cm2) in the non-A-CXL group and 3 minutes (intensity: 30 mW/cm2, fluence: 5.4 J/cm2) in the A-CXL group. Anterior and posterior cone flattening were compared at 12 months. Multiple regression analysis was performed to establish correlation of age, sex, cone location, and preoperative maximum keratometry (Kmax) values with postoperative flattening at 12 months. RESULTS In the non-A-CXL and A-CXL groups, central cones were the steepest, followed by paracentral and peripheral cones. Both groups showed significant flattening in central (1.54 ± 1.94 and 1.09 ± 1.79 diopters [D]) and paracentral (0.62 ± 1.59 and 0.55 ± 0.98 D) cones only. In the non-A-CXL group, there was a positive correlation between postoperative flattening and preoperative Kmax values, whereas paracentral and peripheral cone locations were negatively related. In the A-CXL group, only paracentral location was negatively correlated to postoperative flattening and showed posterior cone steepening at 12 months. CONCLUSIONS Although central cones were the steepest in both groups, there was no difference in postoperative flattening between the groups for all cone locations. In the non-A-CXL group, postoperative flattening was proportional to preoperative Kmax values in central cones and was less with paracentral and peripheral locations. With A-CXL, postoperative flattening was less only with paracentral location. In the A-CXL group, significant posterior cone steepening was noticed only in paracentral cones. [J Refract Surg. 2022;38(5):310-316.].
Collapse
|
3
|
Gokul A, Ziaei M, Mathan JJ, Han JV, Misra SL, Patel DV, McGhee CNJ. The Aotearoa Research Into Keratoconus Study: Geographic Distribution, Demographics, and Clinical Characteristics of Keratoconus in New Zealand. Cornea 2022; 41:16-22. [PMID: 33630812 DOI: 10.1097/ico.0000000000002672] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 12/06/2020] [Indexed: 11/27/2022]
Abstract
PURPOSE To investigate the epidemiologic, demographic, and basic clinical characteristics of individuals with keratoconus managed by optometrists in New Zealand (NZ)/Aotearoa. METHODS A prospective, longitudinal, nationwide, survey protocol was completed for every patient with keratoconus who underwent a consultation with participating optometrists in a 2-year period. Data for each patient included date of birth, sex, self-reported ethnicity, new or previous diagnosis, uncorrected (UCVA) and best-corrected visual acuity (BCVA), type of refractive correction required to obtain BCVA and keratometric readings obtained using keratometry or computerized topography. RESULTS One thousand eight hundred sixty-nine cases were identified, with a mean age of 41.0 ± 15.7 years, 56.4% being men, and 87.3% with previous diagnosis. The distribution of cases was skewed toward Auckland (41.6%), Waikato (21.3%), Wellington (16.8%), and Bay of Plenty (13.3%). Self-reported ethnicities were predominantly NZ European (54.4%), Māori (24.7%), and Pacific Peoples (15.5%), disproportionate to the general population profile (74.0%, 14.9%, and 7.4% respectively). Most eyes (64.3%) were managed with rigid contact lenses (corneal lens in 34.2%). The mean K-mean was 49.0 ± 5.7 D. The mean UCVA was 6/42 and BCVA was 6/9. Māori and Pacific Peoples had both the highest K-mean and proportions of eyes graded stage IV on the Amsler-Krumeich scale. CONCLUSIONS The results indicate that keratoconus is relatively common in NZ with at least 1869 patients managed by optometrists in 2 years. Most eyes had mild to moderate disease; however, Māori and Pacific Peoples seem to have greater disease severity. An ethnic predilection is apparent, with Māori and Pacific Peoples overrepresented relative to their population proportions, reinforcing a long-held clinical suspicion.
Collapse
Affiliation(s)
- Akilesh Gokul
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | | | | | | | | | | | | |
Collapse
|
4
|
Ziaei M, Yoon JJ, Vellara HR, Gokul A, Meyer JJ, Thakur SS, McGhee CN, Patel DV. Prospective one year study of corneal biomechanical changes following high intensity, accelerated cornea cross-linking in patients with keratoconus using a non-contact tonometer. Eur J Ophthalmol 2021; 32:11206721211069740. [PMID: 34964368 DOI: 10.1177/11206721211069740] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
PURPOSE To characterize corneal biomechanical properties utilizing a dynamic ultra-high-speed Scheimpflug camera equipped with a non-contact tonometer (CorVis ST, CST) in keratoconic corneas following continuous high intensity, high irradiance corneal cross-linking. DESIGN Prospective longitudinal single-centre study at a tertiary referral center. METHODS Corneal biomechanical properties were measured in patients with progressive keratoconus undergoing high intensity (30 mW/cm2), high irradiance (5.4 J/cm2), accelerated corneal cross-linking with continuous exposure to ultraviolet-A for 4 min. CST was used to assess corneal biomechanical properties pre-operatively and at 1, 3, 6 and 12 months post-operatively. CST output videos were further analyzed using several previously reported algorithms. RESULTS A total of 25 eyes of 25 participants were examined. The mean age of participants was 20.9 ± 5.3 years; 56% were male and 80% were of Māori or Pacific Island origin. Energy absorbed area (mN mm), was the only significantly changed parameter compared to baseline at all time points measuring 3.61 ± 1.19 preoperatively, 2.81 ± 1.15 at 1 month (p = 0.037), 2.79 ± 0.81 (p = 0.033) at 3 months, 2.76 ± 0.95 (p = 0.028) at 6 months and 2.71 ± 1.18 (p = 0.016) at 12 months. CONCLUSIONS The significant difference between the pre and post-operative energy absorbed area appears to reflect changes in corneal viscous properties that occur following corneal cross-linking.
Collapse
Affiliation(s)
- Mohammed Ziaei
- Department of Ophthalmology, 56381University of Auckland, New Zealand
| | - Jinny J Yoon
- Department of Ophthalmology, 56381University of Auckland, New Zealand
| | - Hans R Vellara
- Department of Ophthalmology, 56381University of Auckland, New Zealand
| | - Akilesh Gokul
- Department of Ophthalmology, 56381University of Auckland, New Zealand
| | - Jay J Meyer
- Department of Ophthalmology, 56381University of Auckland, New Zealand
| | - Sachin S Thakur
- Department of Ophthalmology, 56381University of Auckland, New Zealand
| | - Charles Nj McGhee
- Department of Ophthalmology, 56381University of Auckland, New Zealand
| | - Dipika V Patel
- Department of Ophthalmology, 56381University of Auckland, New Zealand
| |
Collapse
|
5
|
Li Y, Gokul A, McGhee C, Ziaei M. Repeatability of corneal and epithelial thickness measurements with anterior segment optical coherence tomography in keratoconus. PLoS One 2021; 16:e0248350. [PMID: 34143790 PMCID: PMC8213071 DOI: 10.1371/journal.pone.0248350] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Accepted: 02/24/2021] [Indexed: 11/18/2022] Open
Abstract
PURPOSE To investigate the repeatability in corneal thickness (CT) and epithelial thickness (ET) measurements using spectral domain anterior segment optical coherence tomography (AS-OCT, REVO NX, Optopol) in keratoconus, and examine the effect of corneal crosslinking (CXL) on repeatability. METHODS A cross-sectional study of 259 eyes of 212 patients with keratoconus attending the corneal disease clinic at a university hospital tertiary referral center were enrolled. Two groups were analysed: eyes with no prior history of CXL (Group A) and eyes with prior CXL (Group B). Repeatability of measurements was assessed using the intraclass correlation coefficient (ICC) and coefficient of variation (CV). RESULTS In Group A, central corneal thickness (CCT) was 472.18 ± 45.41μm, and the ET was found to be the thinnest in the inferior-temporal aspect at 51.79 ± 5.97μm and thickest at the superior-nasal aspect at 56.07 ± 5.70μm. In Group B, CCT was 465.11± 42.28μm, and the ET was the thinnest at the inferior-temporal aspect at 50.63 ± 5.52μm and thickest at the superior aspect at 56.80 ± 6.39μm. When evaluating CT measurements, ICC was above 0.86 and 0.83 for Group A and Group B respectively. When evaluating ET measurements, ICC was above 0.82 for both groups. CXL had no statistically significant impact on the repeatability of measurements. CONCLUSIONS AS-OCT provides repeatable CT and ET measurements in the central and peripheral cornea in patients with keratoconus. Repeatability is not affected by a history of CXL.
Collapse
Affiliation(s)
- Ye Li
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Akilesh Gokul
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Charles McGhee
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Mohammed Ziaei
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| |
Collapse
|
6
|
Measurement of In Vivo Biomechanical Changes Attributable to Epithelial Removal in Keratoconus Using a Noncontact Tonometer. Cornea 2021; 39:946-951. [PMID: 32355111 DOI: 10.1097/ico.0000000000002344] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
PURPOSE To compare the biomechanical properties of the cornea after epithelial removal in eyes with keratoconus undergoing corneal cross-linking. METHODS Prospective interventional case series at a university hospital tertiary referral center. Corneal biomechanical properties were measured in patients with keratoconus undergoing corneal cross-linking, immediately before and after epithelial debridement by using a dynamic ultrahigh-speed Scheimpflug camera equipped with a noncontact tonometer. RESULTS The study comprised 45 eyes of 45 patients with a mean age of 19.6 ± 4.9 years (range 14-34). The cornea was found to be 23.7 ± 15.7 μm thinner after epithelial removal (P < 0.01). Corneal stiffness was reduced after epithelial removal as demonstrated by a significant decrease of parameters such as stiffness parameter A1 (12.31, P < 0.01), stiffness parameter-highest concavity (2.25, P < 0.01), A1 length (0.13 mm, P = 0.04), highest concavity radius of curvature (0.26 mm, P = 0.01), highest concavity time (0.22 ms, P = 0.04) and an increase in A1 velocity (-0.01 m/s, P = 0.01), A1 deformation amplitude (-0.03 mm, P ≤ 0.01), A1 deflection length (-0.32 mm, P < 0.01), A2 deformation amplitude (-0.03 mm, P = 0.01), and A2 deflection length (-1.00 mm, P < 0.01). There were no significant differences in biomechanical intraocular pressure (0.15 mm Hg, P = 0.78), deformation amplitude (0.03, P = 0.54), maximum inverse radius (-0.01 mm, P = 0.57), and whole eye movement length (-0.02 mm, P = 0.12). CONCLUSIONS Dynamic ultrahigh-speed Scheimpflug camera equipped with a noncontact tonometer offers an alternative method for in vivo measurements of the epithelial layer's contribution to corneal biomechanical properties. Our results suggest that corneal epithelium may play a more significant role in corneal biomechanical properties in patients with keratoconus than previously described.
Collapse
|
7
|
Li Y, Gokul A, McGhee C, Ziaei M. Repeatability and agreement of biometric measurements using spectral domain anterior segment optical coherence tomography and Scheimpflug tomography in keratoconus. PLoS One 2021; 16:e0248659. [PMID: 34019547 PMCID: PMC8139453 DOI: 10.1371/journal.pone.0248659] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Accepted: 04/30/2021] [Indexed: 11/25/2022] Open
Abstract
Purpose To compare the repeatability and agreement in biometric measurements using Spectral Domain Anterior Segment OCT (AS-OCT, REVO-NX, Optopol) and Scheimpflug tomography (Pentacam-AXL, Oculus) in keratoconus. Methods Prospective case series at a university hospital tertiary center. Axial length (AL), anterior chamber depth (ACD), central corneal thickness (CCT), and thinnest corneal thickness (TCT) were measured using both devices in patients with keratoconus. Three groups were analyzed: eyes with no prior crosslinking or contact lens wear (Group A), eyes with prior crosslinking (Group B), and eyes with prior contact lens wear (Group C). Repeatability and agreement of measurements were analyzed. Results The study comprised of 214 eyes of 157 subjects. In Group A (n = 95 eyes), Group B (n = 86 eyes), and Group C (n = 33 eyes), intraclass correlation coefficient (ICC) was higher than 0.90 for all examined parameters, except for ACD readings in Group A with the REVO-NX (ICC = 0.83). Differences in ACD, TCT, and CCT were significantly different between the two devices for Groups A, B and C (p<0.05). AL measurements differed significantly in Groups A and B (p<0.05) but not in Group C (p = 0.18). Repeatability did not vary significantly between Groups A, B, or C in any parameter with both devices (p>0.05). There was poor agreement between the two devices across all parameters (p<0.05). Conclusions Both devices demonstrated good repeatability but poor agreement across AL, ACD, CCT and TCT measurements. There was no significant difference in repeatability in virgin eyes compared to eyes with prior crosslinking or contact lens wear, however, the interchangeable use of the two devices is not recommended.
Collapse
Affiliation(s)
- Ye Li
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Akilesh Gokul
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Charles McGhee
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Mohammed Ziaei
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
- * E-mail:
| |
Collapse
|
8
|
Hayes S, Morgan SR, Meek KM. Keratoconus: cross-linking the window of the eye. THERAPEUTIC ADVANCES IN RARE DISEASE 2021; 2:26330040211003573. [PMID: 37181107 PMCID: PMC10032441 DOI: 10.1177/26330040211003573] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 02/25/2021] [Indexed: 05/16/2023]
Abstract
Keratoconus is a condition in which the cornea progressively thins and weakens, leading to severe, irregular astigmatism and a significant reduction in quality of life. Although the precise cause of keratoconus is still not known, biochemical and structural studies indicate that overactive enzymes within the cornea break down the constituent proteins (collagen and proteoglycans) and cause the tissue to weaken. As the disease develops, collagen fibres slip past each other and are redistributed across the cornea, causing it to change shape. In recent years, it was discovered that the photochemical induction of cross-links within the corneal extracellular matrix, through the use of riboflavin and ultraviolet (UVA) light, could increase the strength and enzymatic resistance of the tissue and thereby halt keratoconus progression. Worldwide acceptance and use of riboflavin/UVA corneal cross-linking therapy for halting keratoconus progression has increased rapidly, in accordance with the growing body of evidence supporting its long-term effectiveness. This review focusses on the inception of riboflavin/UVA corneal cross-linking therapy for keratoconus, its clinical effectiveness and the latest scientific advances aimed at reducing patient treatment time, improving patient comfort and increasing patient eligibility for treatment. Plain language summary Review of current treatments using cross-linking to halt the progress of keratoconus Keratoconus is a disease in which the curved cornea, the transparent window at the front of the eye, weakens, bulges forward into a cone-shape and becomes thinner. This change of curvature means that light is not focussed onto the retina correctly and vision is progressively impaired. Traditionally, the effects of early keratoconus were alleviated by using glasses, specialist contact lenses, rings inserted into the cornea and in severe cases, by performing a corneal transplant. However, it was discovered that by inducing chemical bonds called cross-links within the cornea, the tissue could be strengthened and further thinning and shape changes prevented. The standard cross-linking procedure takes over an hour to perform and involves the removal of the cells at the front of the cornea, followed by the application of Vitamin B2 eye drops and low energy ultraviolet light (UVA) to create new cross-links within the tissue. Clinical trials have shown this standard procedure to be safe and effective at halting keratoconus progression. However, there are many treatment modifications currently under investigation that aim to reduce patient treatment time and increase comfort, such as accelerated cross-linking procedures and protocols that do not require removal of the surface cells. This review describes the different techniques being developed to carry out corneal cross-linking efficiently and painlessly, to halt keratoconus progression and avoid the need for expensive surgery.
Collapse
Affiliation(s)
- Sally Hayes
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ. UK
| | - Siân R Morgan
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK
| | - Keith M Meek
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK
| |
Collapse
|
9
|
Li Y, Lu LM, Gokul A, Ziaei M. Case Report: Successful Corneal Crosslinking in a Patient with Corneal Ectasia Associated with Stevens-Johnson Syndrome. Optom Vis Sci 2021; 98:13-17. [PMID: 33394926 DOI: 10.1097/opx.0000000000001623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
SIGNIFICANCE Corneal ectasia can be a complication of Stevens-Johnson syndrome. When detected in a timely manner, corneal crosslinking can be a safe treatment. This is an important association to highlight that early diagnosis and treatment can prevent the need for invasive surgical procedures such as keratoplasty. PURPOSE This study aimed to report a successful accelerated epithelium-off corneal crosslinking in a rare case of corneal ectasia secondary to Stevens-Johnson syndrome. CASE REPORT A 25-year-old Indian man presented with a progressive visual acuity decline 5 years after an acute episode of Stevens-Johnson syndrome secondary to penicillin ingestion. Serial tomography scans confirmed the diagnosis of corneal ectasia. After the preparation of the ocular surface, which was deemed to have a mild degree of limbal stem cell deficiency, with frequent preservative-free lubrication and steroid use, accelerated epithelium-off crosslinking was performed with 4 minutes of continuous ultraviolet-A exposure at 30 mW/cm2 and a total energy dose of 7.2 J/cm2. Complete re-epithelialization was observed at 72 hours after crosslinking with no complications. Corneal tomography 15 months after treatment showed stabilization of ectasia, with improvement in visual acuity. CONCLUSIONS Corneal ectasia is a rare but important complication of Stevens-Johnson syndrome. Accelerated epithelium-off crosslinking treatment can be considered in patients with a compromised ocular surface after Stevens-Johnson syndrome. Pre-operative optimization of the ocular surface and vigilant monitoring in the early post-operative period are recommended for the prevention of complications.
Collapse
Affiliation(s)
- Ye Li
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | | | | | | |
Collapse
|
10
|
Ziaei M, Gokul A, Vellara H, Patel D, McGhee CN. Prospective two year study of changes in corneal density following transepithelial pulsed, epithelium-off continuous and epithelium-off pulsed, corneal crosslinking for keratoconus. Cont Lens Anterior Eye 2020; 43:458-464. [DOI: 10.1016/j.clae.2020.03.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 03/10/2020] [Accepted: 03/10/2020] [Indexed: 12/18/2022]
|
11
|
Ziaei M, Gokul A, Vellara H, Patel DV, McGhee CNJ. Measurement of refractive, wavefront, topographic, and keratometric changes attributable to epithelial removal in keratoconus. Can J Ophthalmol 2020; 56:6-11. [PMID: 32777204 DOI: 10.1016/j.jcjo.2020.06.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 06/20/2020] [Accepted: 06/29/2020] [Indexed: 10/23/2022]
Abstract
OBJECTIVE The corneal epithelium is able to mask topographic and keratometric abnormalities of the underlying Bowman layer in keratoconus, but its contribution to refractive and wavefront parameters has not yet been studied. This study compared the refractive and aberrometric features of the corneal epithelium and Bowman layer in eyes with keratoconus before and after epithelial debridement. METHODS Corneal refractive and wavefront variables were measured in patients with keratoconus undergoing corneal crosslinking-immediately before and after epithelial debridement using a third-generation combined corneal topographer, autorefractor, and aberrometer. RESULTS After epithelial debridement, there were significant changes in spherical equivalent (-1.37 D; p < 0.01) and asphericity (-0.64; p = 0.03). The mean difference in the magnitude of epithelium-induced astigmatism in the 3rd and 5th central millimeter rings was 0.44 ± 3.20 D × 8 and 0.43 ± 2.75 D × 21 (positive cylinder), respectively. Corneal astigmatism axis shifted in the against-the-rule orientation after epithelial debridement. There were no significant changes in any corneal higher-order aberration parameter after epithelial debridement (p > 0.05). CONCLUSIONS In eyes with keratoconus, epithelial debridement increased the magnitude of anterior corneal prolateness and tended to increase astigmatism and shift its axis toward the against-the-rule orientation. This study supports the notion that the corneal epithelium smooths underlying Bowman layer irregularity in keratoconus.
Collapse
Affiliation(s)
- Mohammed Ziaei
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand..
| | - Akilesh Gokul
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Hans Vellara
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Dipika V Patel
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Charles N J McGhee
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| |
Collapse
|
12
|
Ziaei M, Vellara HR, Gokul A, Ali NQ, McGhee CNJ, Patel DV. Comparison of corneal biomechanical properties following penetrating keratoplasty and deep anterior lamellar keratoplasty for keratoconus. Clin Exp Ophthalmol 2019; 48:174-182. [PMID: 31705767 DOI: 10.1111/ceo.13677] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 10/15/2019] [Accepted: 10/30/2019] [Indexed: 11/28/2022]
Abstract
IMPORTANCE Keratoplasty is a surgical procedure to create a more regular optical surface following biomechanical weakening of the cornea in keratoconus. The ideal keratoplasty procedure should also restore corneal biomechanics to that of the healthy cornea. BACKGROUND This study aimed to evaluate and compare the biomechanical properties of corneas following penetrating keratoplasty (PKP) and predescematic deep anterior lamellar keratoplasty (DALK) to those of healthy eyes. DESIGN Prospective cross-sectional study. PARTICIPANTS Two cohorts of post-keratoplasty eyes (42 eyes with PKP and 27 eyes with DALK) with each other, and with a cohort of 152 healthy eyes. METHODS All eyes were examined by slit-lamp biomicroscopy, tomography, anterior segment-OCT and non-contact tonometry CorVis ST (CST). MAIN OUTCOME MEASURES CST biomechanical parameters, maximum corneal deformation (MCD) and corneal energy dissipation were compared between keratoplasty techniques, and with healthy eyes. RESULTS The mean age of participants with PKP and DALK were 35 ± 13.7 and 36.1 ± 12.6 years, respectively. None of the CST parameters were significantly different between PKP and DALK eyes. However, when compared to healthy corneas, numerous parameters were significantly different for both keratoplasty techniques. Of note, MCD was significantly higher in PKP compared to DALK and healthy corneas, after controlling for co-factors. CONCLUSIONS AND RELEVANCE Neither type of keratoplasty technique utilized in keratoconus completely restored corneal biomechanical properties to that of healthy corneas. However, PKP resulted in a greater number of parameters significantly different to healthy corneas, compared to DALK.
Collapse
Affiliation(s)
- Mohammed Ziaei
- Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Hans R Vellara
- Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Akilesh Gokul
- Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Noor Q Ali
- Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Charles N J McGhee
- Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Dipika V Patel
- Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| |
Collapse
|
13
|
Ziaei M, Vellara H, Gokul A, Patel D, McGhee CNJ. Prospective 2-year study of accelerated pulsed transepithelial corneal crosslinking outcomes for Keratoconus. Eye (Lond) 2019; 33:1897-1903. [PMID: 31273313 DOI: 10.1038/s41433-019-0502-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 01/27/2019] [Accepted: 04/24/2019] [Indexed: 01/17/2023] Open
Abstract
AIMS To report 2-year outcomes of transepithelial, accelerated, pulsed, corneal crosslinking (t-ACXL) for patients with progressive keratoconus. METHODS Prospective, interventional case series at a university hospital tertiary referral centre. Forty eyes with progressive keratoconus undergoing t-ACXL were included. Treatment was performed with pulsed illumination (1 s on/1 s off) using 45 mW/cm2 for 5 min and 20 s, for a surface dose of 7.2 J cm2. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent (MRSE), corneal tomography, anterior segment optical coherence tomography (OCT) and confocal microscopy were evaluated preoperatively and at 12 and 24 months postoperatively. RESULTS The mean patient age was 23.32 ± 5.18 years (SD) (range 14-42 years). The mean CDVA significantly improved from 0.38 ± 0.32 logMAR at baseline to 0.30 ± 0.21 logMAR at 24 months (P < 0.01). There was no significant difference in UDVA, MRSE, asymmetry indices, tomographic parameters and endothelial density. The improvement in visual acuity was inversely correlated with preoperative CDVA and preoperative KMax. No complications were encountered. CONCLUSIONS In this prospective study, t-ACXL appeared safe and effective in halting progression of keratoconus within a follow-up period of 24 months.
Collapse
Affiliation(s)
- Mohammed Ziaei
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand.
| | - Hans Vellara
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
| | - Akilesh Gokul
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
| | - Dipika Patel
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
| | - Charles N J McGhee
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
| |
Collapse
|