Micropulse Transscleral Cyclophotocoagulation in Non-Incisional Eyes with Ocular Hypertension and Primary Open-Angle Glaucoma.

Purpose: To investigate the safety and effectiveness of micropulse transscleral cyclophotocoagulation (MPTSCPC) in non-incisional eyes with ocular hypertension (OHT) and early, moderate, and severe primary open-angle glaucoma (POAG). Methods: Retrospective cohort study of eyes that underwent MPTSCPC from 2016 to 2019 at an outpatient clinic in Canada. Eyes were excluded if any incisional procedures, except cataract surgery, were performed prior to MPTSCPC treatment. Laser power ranged from 900 to 2500mW. Results: A total of 153 eyes from 93 patients were included (OHT n=22; early POAG n=46; moderate POAG n=35; severe POAG n=50). The baseline IOP was 18.37 ± 4.76mmHg in the total cohort. All cohorts experienced a significant mean IOP reduction by final follow-up (total p<0.001; OHT p=0.003; early POAG p<0.001; moderate POAG p=0.022; severe POAG p=0.015). Overall, 52.9% of eyes achieved an IOP reduction of ≥20% from baseline to final follow-up (OHT 59.1%; early POAG 58.7%; moderate POAG 45.7%; severe POAG 50.0%). There was worsening in best-corrected visual acuity in the total cohort (mean difference=0.11 ± 0.36 logMAR, p=0.11), mostly attributable to cataract progression (34.1% of phakic eyes) and ocular surface disease (7.2%). The number of topical medications and drug classes remained unchanged in the total cohort (p=0.425 and p=0.791, respectively). Twenty-two eyes (14.4%) required retreatment, which provided an additional IOP reduction of 1.26mmHg (p=0.344). By final follow-up, 8 eyes (5.2%) required escalation to incisional procedures. Conclusion: MPTSCPC is a safe and effective adjunct IOP-lowering treatment in non-incisional eyes with OHT and POAG.

Feasibility of an artificial intelligence phone call for postoperative care following cataract surgery in a diverse population: two phase prospective study protocol.

INTRODUCTION: Artificial intelligence (AI) development has led to improvements in many areas of medicine. Canada has workforce pressures in delivering cataract care. A potential solution is using AI technology that can automate care delivery, increase effectiveness and decrease burdens placed on patients and the healthcare system. This study assesses the use of 'Dora', an example of an AI assistant that is able to deliver a regulated autonomous, voice-based, natural-language consultation with patients over the telephone. Dora is used in routine practice in the UK, but this study seeks to assess the safety, usability, acceptability and cost-effectiveness of using the technology in Canada. METHODS AND ANALYSIS: This is a two-phase prospective single-centred trial. An expected 250 patients will be recruited for each phase of the study. For Phase I of the study, Dora will phone patients at postoperative week 1 and for Phase II of the study, Dora will phone patients within 24hours of their cataract surgery and again at postoperative week 1. We will evaluate the agreement between Dora and a supervising clinician regarding the need for further review based on the patients' symptoms. A random sample of patients will undergo the System Usability Scale followed by an extended semi-structured interview. The primary outcome of agreement between Dora and the supervisor will be assessed using the kappa statistic. Qualitative data from the interviews will further gauge patient opinions about Dora's usability, appropriateness and level of satisfaction. ETHICS AND DISSEMINATION: Research Ethics Board William Osler Health System (ID: 22-0044) has approved this study and will be conducted by guidelines of Declaration of Helsinki. Master-linking sheet will contain the patient chart identification (ID), full name, date of birth and study ID. Results will be shared through peer-reviewed journals and presentations at conferences.

Anterior chamber cytokine production and postoperative macular edema in patients with diabetes undergoing FLACS.

PURPOSE: To evaluate the effect of femtosecond laser-assisted cataract surgery (FLACS) and manual cataract surgery (MCS) on proinflammatory cytokine expression in patients with diabetes vs nondiabetic patients. SETTING: Outpatient surgical center in Vaughan, Ontario, Canada. DESIGN: Prospective cohort study. METHODS: Patients with diabetes and nondiabetic patients undergoing noncomplicated MCS or FLACS were assigned into 4 cohorts: MCS nondiabetic (n = 30), FLACS nondiabetic (n = 42), MCS diabetic (n = 40), and FLACS diabetic (n = 40). Aqueous humor inflammatory mediator concentrations were evaluated at MCS onset and after femtosecond laser treatment. The presence of cystoid macular edema, anterior chamber (AC) inflammation, central retinal thickness, macular volume, and retinal microvascular changes (through optical coherence tomography angiography) were evaluated preoperatively and on postoperative day 1, week 1, month 1 (POM1), and month 3 (POM3). RESULTS: Patients with diabetes receiving FLACS had a higher concentration of interleukin (IL)-7, IL-13, and interferon-induced protein-10 than MCS diabetic patients; they also demonstrated higher levels of vascular endothelial growth factor and lower levels of interferon (IFN)-γ, granulocyte colony-stimulating factor, and IFN-α2 compared with MCS nondiabetic patients. Macular volume appeared to be significantly higher in MCS diabetic vs MCS non-diabetic patients at POM1 and between FLACS diabetic vs FLACS nondiabetic patients at POM3. There were no other significant differences between the cohorts for any parameter. CONCLUSIONS: FLACS use in patients with diabetes demonstrated some differences in AC cytokine expression compared with non-diabetic FLACS or diabetic patients undergoing MCS; however, there was no increase in clinical inflammatory biomarkers. FLACS seems to be a safe technique to use in patients with diabetes.

Comparison of pain perception in patients undergoing manual cataract surgery versus refractive laser-assisted cataract surgery.

OBJECTIVES: To assess pain perception in patients undergoing manual cataract surgery versus femtosecond laser-assisted cataract surgery (FLACS) and pain perception of patients receiving anaesthesia at 2 different time points during the FLACS procedure. We also aimed to assess the factors affecting pain perception in these different study groups. DESIGN: Prospective cohort comparison of patient-selected surgical approach. PARTICIPANTS: Patients undergoing delayed sequential bilateral cataract surgery at an ambulatory surgical centre in Ontario. METHODS: Patients were assigned to 3 groups: a manual cataract surgery cohort (n = 30) and 2 FLACS cohorts, those who received neurolept anaesthesia just prior to draping for phacoemulsification (FLACS standard cohort; n = 38) and those who received neurolept anaesthesia prior to the femtosecond laser part of the procedure (FLACS early cohort; n = 35). Outcome metrics included pain scores on the visual analogue scale on postoperative day 0 and at postoperative week 1. Secondary outcome measures included anxiety scores, surgeon or anaesthesiologist patient cooperation scores, ocular metrics, and perioperative systemic vitals. RESULTS: There were no significant differences in pain perception on postoperative day 0 and at postoperative week 1 among the manual cataract surgery and FLACS standard cohorts (p = 0.94 and p = 0.72, respectively) or FLACS early and FLACS standard cohorts (p = 0.76 and p = 0.67, respectively). Patients had higher pain scores during second-eye procedures than first-eye procedures. CONCLUSIONS: Cataract surgery technique or timing of anaesthesia for FLACS procedures does not affect pain perception postoperatively. Second-eye procedures are associated with higher pain scores than first-eye procedures.

Autologous Platelet-Rich Plasma Drops for Evaporative Dry Eye Disease from Meibomian Gland Dysfunction: A Pilot Study.

Purpose: To evaluate the effects of autologous platelet-rich plasma (PRP) drops for evaporative dry eye (EDE) disease from meibomian gland dysfunction (MGD). Methods: This is a retrospective, consecutive case series of 20 eyes of 10 patients with EDE from MGD treated with PRP drops from November 2020 to November 2021 at a single outpatient clinic in Ontario, Canada. PRP drops were prepared from whole blood using a two-step centrifugation method. Patients were instructed to instill these drops six times daily for 4 weeks. The Canadian Dry Eye Assessment (CDEA) questionnaire score, patient subjective assessment (PSA) score, first and average non-invasive break-up times (f/a NIBUT), tear meniscus height (TMH), bulbar redness (BR), and meibograph grade (MG) were measured before and after the treatment course. Results: Significant improvements in dry eye symptoms and tear film parameters were observed. Dry eye symptoms significantly improved as per the CDEA (mean difference (MD) = -5.45, 95% confidence interval (CI) = [-7.9, -3.1], p<0.001) and PSA (MD = -2.6, 95% CI = [-3.9, -1.2], p<0.001). There were significant improvements in tear film parameters including fNIBUT (MD = 3.85s, 95% CI = [1.2, 6.8], p=0.006), aNIBUT (MD = -6.81s, 95% CI = [5.7, 11.1], p<0.001) and TMH (MD = 0.08, 95% CI = [0.003, 0.2], p=0.045). There was an improvement in conjunctival injection as measured by BR (MD = -0.36, 95% CI = [-0.4, -0.15], p=0.373). Five eyes experienced a one-grade improvement in MG (p=0.453), and none experienced worsening in MG with treatment. No temporary or permanent adverse effects were noted. Conclusion: Four weeks of PRP therapy resulted in significant functional improvements in dry eye symptoms and tear film quality and quantity. Improvements in conjunctival injection and microstructural improvements in meibomian glands were also observed in some eyes. Overall, PRP is a promising treatment option for patients with EDE from MGD refractory to conventional treatments.

Comparison of Barrett Toric Calculations Using Measured and Predicted Posterior Corneal Astigmatism in Cataract Surgery Patients.

Aim: To compare residual astigmatism prediction errors across Barrett toric calculations using predicted posterior corneal astigmatism (PCA) and PCA measured using the IOL Master 700 with total keratometry (IOLM). Methods: A retrospective cohort study was undertaken on patients with corneal astigmatism and no other ocular comorbidities that underwent uneventful refractive femtosecond laser-assisted cataract surgery with toric IOL implantation between May 2019 and November 2019. Toric calculations were performed using the Barrett toric calculator and the following values: predicted PCA with anterior corneal measurements from Pentacam, IOLM standard keratometry (SK), OPD scan, and median measurements from these devices; predicted PCA with IOLM total keratometry (TK); and measured PCA with IOLM SK or IOLM TK. Residual astigmatism prediction error was calculated for each device and method of calculation at postoperative month 1 and 3 using the astigmatism double angle plot tool. Results: A total of 24 eyes, 10 with-the-rule (WTR), 10 against-the-rule (ATR) and 4 oblique astigmatism, from 24 patients were included in this study. PCA ranged from 0.00 to 0.67 D with a mean of 0.24 ± 0.15 D in all eyes. PCA was significantly greater in WTR eyes (0.32 D) compared to ATR eyes (0.16 D; p < 0.05). In ATR eyes, calculations made using IOLM SK and measured PCA had significantly lower total corneal astigmatism and toric IOL cylinder power compared to calculations made using Pentacam and IOLM TK (p < 0.05). No significant difference in mean absolute or centroid residual astigmatism prediction error was observed across devices or calculation methods. The percentage of eyes with absolute astigmatism prediction errors ≤0.5 D was not significantly different across groups. Conclusion: Barrett toric calculations using predicted PCA and PCA measured using IOLM produced comparable residual astigmatism prediction errors. The incorporation of median measurements did not significantly impact calculation accuracy.

Safety and Efficacy of BroadBand Intense Pulsed Light Therapy for Dry Eye Disease with Meibomian Gland Dysfunction.

BACKGROUND: BroadBand light intense pulsed light (BBL-IPL) therapy has shown to reduce hordeolum and blepharitis frequency. This study aims to evaluate the efficacy and safety of BBL-IPL therapy in patients with dry eye disease (DED) from meibomian gland dysfunction (MGD). METHODS: This is a retrospective, consecutive case series of 48 patients with DED from MGD who underwent BBL-IPL therapy from October 2016 to January 2019 at a single, outpatient clinic in Ontario, Canada. Clinical outcomes included first and average non-invasive keratograph tear break-up times (NIKBUT), bulbar redness (BR) scores, tear meniscus heights (TMH), visual acuity (VA) and meibograph grades. Patient-reported outcomes included the Canadian dry eye assessment (CDEA) questionnaire and patient subjective assessment (PSA) scores. Outcomes were measured at baseline and after completion of 4 monthly BBL-IPL sessions. RESULTS: The mean severity of dry eye symptoms as measured by the CDEA and PSA decreased significantly from 19.78 ± 9.62 to 12.08 ± 7.40 (p<0.001) and from 7.65 ± 1.74 to 4.77 ± 2.03 (p<0.001), respectively. Twenty-five percent of patients reported no dry eye symptoms after treatment. The meibograph grade improved significantly in both eyes (p<0.001). Approximately 71.0% and 80.1% of patients had an improved meibograph grade in the right and left eye, respectively. Near-significant improvements were observed for BR scores and VA. There was also a trend towards improved first/average NIKBUT and TMH scores. No adverse events were noted. CONCLUSION: BBL-IPL appears to be an effective and safe treatment modality in improving dry eye symptoms and meibomian gland function in patients with DED from MGD.

Evaluating newer generation intraocular lens calculation formulas in manual versus femtosecond laser-assisted cataract surgery.

AIM: To determine the refractive accuracy of the Haigis, Barrett Universal II (Barrett), and Hill-radial basis function 2.0 (Hill-RBF) intraocular lens (IOL) power calculations formulas in eyes undergoing manual cataract surgery (MCS) and refractive femtosecond laser-assisted cataract surgery (ReLACS). METHODS: This was a REB-approved, retrospective interventional comparative case series of 158 eyes of 158 patients who had preoperative biometry completed using the IOL Master 700 and underwent implantation of a Tecnis IOL following uncomplicated cataract surgery using either MCS or ReLACS. Target spherical equivalence (SE) was predicted using the Haigis, Barrett, and Hill-RBF formulas. An older generation formula (Hoffer Q) was included in the analysis. Mean refractive error (ME) was calculated one month postoperatively. The lens factors of all formulas were retrospectively optimized to set the ME to 0 for each formula across all eyes. The median absolute errors (MedAE) and the proportion of eyes achieving an absolute error (AE) within 0.5 diopters (D) were compared between the two formulas among MCS and ReLACS eyes, respectively. RESULTS: Of the 158 eyes studied, 64 eyes underwent MCS and 94 eyes underwent ReLACS. Among MCS eyes, the MedAE did not differ between the formulas (P=0.59), however among ReLACS eyes, Barrett and Hill-RBF were more accurate (P=0.001). Barrett and Hill-RBF were both more likely to yield AE<0.5 D among both groups (P<0.001). CONCLUSION: The Barrett and Hill-RBF formula lead to greater refractive accuracy and likelihood of refractive success when compare to Haigis in eyes undergoing ReLACS.

Astigmatic Outcomes of Single, Non-Paired Intrastromal Limbal Relaxing Incisions During Femtosecond Laser-Assisted Cataract Surgery Based on a Custom Nomogram.

PURPOSE: To determine astigmatic changes of intrastromal limbal-relaxing incisions (LRIs) performed during femtosecond laser-assisted cataract surgery (FLACS). DESIGN: Retrospective case series. PATIENTS AND METHODS: Patients undergoing FLACS with adjunctive astigmatism management with intrastromal LRIs were included. All eyes had preoperative corneal cylinder (Kcyl) ≥0.20 D on ocular biometry. An intrastromal LRI nomogram of single, non-paired LRIs placed at the 9 mm optical zone was used. Keratometry was measured preoperatively, and postoperatively at 1 week, 1 month, and 3 months (POM3). Alpins astigmatism analysis was used to calculate target-induced astigmatism (TIA, equivalent to preoperative Kcyl), surgically induced astigmatism (SIA), difference vectors (DV), and correction indices (CI). Secondary analysis included multivariable binary logistic regression to determine clinical factors associated with corrections >125% (CI > 1.25). RESULTS: A total of 154 eyes (125 patients) were studied. Mean preoperative Kcyl was 0.87±0.42 D (SD), which did not significantly differ from POM3 Kcyl (0.87±0.51 D, p=0.470). Only the against-the-rule (ATR) subgroup demonstrated a small but significant reduction in Kcyl from preoperative (0.96±0.51D) to POM3 (0.89±0.55D, p=0.032). Sixteen eyes (10.4%) had Kcyl ≤0.5 D preoperatively, compared to 46 eyes (29.9%) at POM3 (p<0.0001). Mean SIA was 0.80±0.52 D. Mean DV was 0.85±0.47. Mean CI was 0.79. Fifty-one eyes (33%) had astigmatism correction >125%. On multivariable regression analysis, ATR astigmatism class (p=0.026) and lower arc lengths (30º) (p=0.005) were associated with correction >125%. Lower preoperative corneal astigmatism was inversely correlated with CI (p<0.001). CONCLUSION: Although intrastromal LRIs can be conveniently performed during FLACS and appear safe, only patients with ATR astigmatism demonstrated a significant reduction in corneal astigmatism 3-months postoperatively under the current nomogram. Areas for future refinements to the nomogram were identified.

Comparison of Surgically Induced Astigmatism and Corneal Morphological Features Between Femtosecond Laser and Manual Clear Corneal Incisions.

PURPOSE: To assess corneal morphologic changes and surgically induced astigmatism (SIA) following clear corneal incisions (CCIs) created manually or with the Catalys femtosecond laser (Johnson & Johnson Vision, Santa Ana, CA). METHODS: In this retrospective cohort analysis, patients undergoing femtosecond laser-assisted cataract surgery (FLACS) or manual cataract surgery between June and September 2018 from a single surgical center in Toronto, Canada, were considered for inclusion. Postoperative corneal astigmatism values were compared to preoperative astigmatism indices to determine the SIA at the postoperative 3-month (POM3) mark using the Alpins vector method. Secondary outcomes included postoperative corrected distance visual acuity (CDVA), central corneal thickness (CCT), and CCI morphology parameters. RESULTS: Refractive outcomes from 104 eyes of 61 patients (54 eyes in the manual group and 50 eyes in the FLACS group) were included. There was no significant difference in POM3 SIA (manual: 0.45 ± 0.28 diopters [D], FLACS: 0.57 ± 0.46 D, P = .11); however, a significantly larger SIA was noted in the FLACS cohort at postoperative 1 week (P = .02) and 1 month (P = .04). FLACS led to a significantly smaller POM3 CCI thickness (P = .006), and CCI position was comparable between the two techniques (P = .44). There were no significant differences between groups in CDVA (P = .19), CCT thickness (P = .20), or phacoemulsification time (P = .59). CONCLUSIONS: There was no significant difference in SIA between FLACS and manual cataract surgery at POM3. With a significantly smaller CCI thickness seen in FLACS cases, and a comparable CCI position, the reason for the increased SIA following laser CCIs in the early postoperative period was unclear. [J Refract Surg. 2019;35(12):796-802.].

Refractive Laser-Assisted Cataract Surgery versus Conventional Manual Surgery: Comparing Efficacy and Safety in 3144 Eyes.

PURPOSE: To report on outcomes of the efficacy and safety in 1 of the largest series of eyes undergoing either conventional manual cataract surgery (MCS) or refractive femtosecond laser-assisted cataract surgery (ReLACS). DESIGN: Retrospective, consecutive, interventional comparative case series. METHODS: This study included 3144 consecutive eyes, of which 1580 were treated via MCS, and 1564 were treated via ReLACS at Uptown Surgical Centre in Vaughan, Ontario, Canada. Preoperative characteristics, best corrected visual acuity (BCVA), mean absolute spherical error (MAE), rates of intraoperative posterior capsular rupture, and postoperative complications were evaluated. RESULTS: Across all eyes, ReLACS was superior to MCS for reducing surgical time (MCS: 7.7 ± 0.1 min vs ReLACS: 6.8 ± 0.1 min, P < 0.001); was less commonly associated with postoperative cystoid macular edema (OR = 0.36, 95% CI: 0.14-0.91, P = 0.031) and more commonly reduced MAE (MCS: 0.60 ± 0.02 diopters (D) vs ReLACS: 0.54 ± 0.02 D, P = 0.02). There were no differences in rates of posterior capsular rupture (P = 0.918), overall postoperative complications (P = 0.088) or final BCVA (P = 0.881). When analyzing a subgroup of more difficult cases (n = 833), ReLACS was superior to MCS for: 1) being more likely to yield an improvement of more than 0.1 logarithm of the minimum angle of resolution BCVA (OR = 1.80, 95% CI: 1.15-2.74, P = 0.01); 2) reducing MAE (MCS: 0.73 ± 0.3 D vs ReLACS: 0.60 ± 0.27 D, P = 0.04); and 3) being more likely to yield an MAE within 0.5 D (OR = 1.61, 95% CI: 1.11-2.33, P = 0.012). CONCLUSIONS: Across all eyes, our results support that ReLACS and MCS yield similar outcomes. However, our results show trends toward a more pronounced benefit of ReLACS compared to MCS when treating more difficult eyes.

The value of color Doppler imaging and intralesional steroid injection in pediatric orbital capillary hemangioma.

BACKGROUND: To evaluate color Doppler imaging (CDI) as the primary imaging modality in the diagnosis of pediatric orbital capillary hemangioma. METHODS: This is a retrospective study of 36 consecutive cases of orbital capillary hemangiomas between January 2006 and July 2011. Data on demographic details, clinical findings, gray-scale ultrasonography, CDI characteristics, treatment, and follow-up period were reviewed. RESULTS: The mean age of onset was 7 weeks. Twenty-nine (81%) lesions presented as eyelid masses, whereas seven (19%) presented as exophthalmos. Nineteen (53%) tumors were located on the upper eyelid, seven (19%) on the lower eyelid, six (17%) in the medial canthus, and one on both upper and lower eyelids. Ultrasonography depicted a heterogeneous, well-defined, irregular tumor with a low or moderate echogenicity. All lesions presented with abundant color blood flow on CDI. The intralesional blood flow had a mean peak systolic velocity of 37.5 ± 24.5 cm/second, and a mean resistance index of 0.69 ± 0.16, representing a shift in the pulse Doppler toward high velocity and high resistance. After a single intratumoral injection of betamethasone, 18 cases (50%) resolved. Additionally, 15 (42%) and four (11%) cases resolved after two injections and three injections, respectively. Only three (8%) masses persisted after three injections within the follow-up period. CONCLUSION: The blood flow characteristics of CDI play a vital role in the differentiation of orbital capillary hemangiomas from other orbital lesions. The availability and lack of adverse effects of CDI enable its utilization in the early clinical diagnosis of pediatric orbital capillary hemangioma.

Solitary fibrous tumor of the orbit: a case series.

PURPOSE: Solitary fibrous tumor (SFT) occurs rarely in the orbit. We present four such cases, representing one of the largest case series reported to date of this rare orbital tumor. METHOD: The four patients ranged from ages 20 to 50, all of whom presented with lid swelling or bulging in the involved eye. All four patients underwent CT scan to confirm the diagnosis of an orbital mass, which was then excised. RESULTS: The tumors of all four specimens contained spindle-shaped cells with bland nuclei and rare mitotic figures. They all stained positively with CD34 and vimentin. Resection margins were positive in two of the four cases. One of these cases demonstrated residual tumor on follow-up CT scan, which remained unchanged at one-year follow-up. No evidence of residual tumor was found in the other three cases, despite one having malignant pathology. CONCLUSION: SFT is a rare and generally benign tumor of the orbit. Immunohistochemical testing with CD34 is necessary to confirm the diagnosis. Although en bloc tumor resection is the definitive treatment, residual tumor may remain stable for some time. However, this must be followed closely if complete resection is not carried out.

Comparison of central corneal thickness measurements by specular microscopy, ultrasound pachymetry, and ultrasound biomicroscopy.

PURPOSE: To compare the reproducibility and mean values of central corneal thickness (CCT) obtained by specular microscopy, ultrasound pachymetry, and ultrasound biomicroscopy (UBM). SETTING: Department of Ophthalmology, University of Toronto, Toronto, Ontario, Canada. METHODS: Thirty-one healthy volunteers were recruited for a sample size of 62 eyes. All subjects had pachymetric measurements by specular microscopy, ultrasound pachymetry, and UBM. Three separate measurements meeting criteria for centrality and perpendicularity were recorded for each eye. RESULTS: The mean CCT by specular microscopy was 572 microm (95% confidence interval (CI), 566-578 microm), which was significantly greater than 550 microm (95% CI, 545-556 microm) (P<.001) and 555 microm (95% CI, 550-560 microm) (P<.001) by ultrasound pachymetry and UBM, respectively. The mean standard deviation (SD) of repeated measurements by specular microscopy was 7.82 microm, which was significantly greater than the mean SDs of 4.14 microm (P<.001) and 3.90 microm (P<.001) by ultrasound pachymetry and UBM, respectively. There was no statistically significant difference between the mean SDs by ultrasound pachymetry and UBM (P=.156). CONCLUSIONS: Although the CCT measurements by specular microscopy were significantly less reproducible than those by ultrasound pachymetry and UBM, the error levels were clinically acceptable. Both ultrasound pachymetry and UBM produced similar CCT measurements, which were significantly less than those generated by specular microscopy. One should be aware of the advantages and limitations of each machine and of possible differences in the CCT measurements by optical and ultrasound pachymetry.