Vinod Gauba

Human Reliability Analysis of Cataract Surgery

OBJECTIVE To evaluate the use of the Human Reliability Analysis of Cataract Surgery tool to identify the frequency and pattern of technical errors observed during phacoemulsification cataract extraction by surgeons with varying levels of experience. DESIGN Observational cohort study. Thirty-three consecutive phacoemulsification cataract operations were performed by 33 different ophthalmic surgeons with varying levels of operative experience: group 1, fewer than 50 procedures; group 2, between 50 and 250 procedures; and group 3, more than 250 procedures. Face and content validity were surveyed by a panel of senior cataract surgeons. The tool was applied to the 33 randomized and anonymous videos by 2 independent assessors trained in error identification and correct tool use. Task analysis using 10 well-defined end points and error identification using 10 external error modes were performed for each case. The main outcome measures were number of errors performed per task, nature of performed errors (executional or procedural), and surgical experience of operating surgeon. RESULTS Analysis of 330 constituent steps of 33 operations identified 228 errors, of which 151 (66.2%) were executional and 77 (33.8%) were procedural. The overall highest error probability was associated with sculpting, followed by fragmentation of the nucleus; this was most evident in group 1. Surgeons in group 3 proportionally performed more errors during removal of soft lens matter than those in group 1 or 2. Surgical experience had a significant effect on the number of errors, with a statistically significant difference among the 3 groups (P < .001). CONCLUSIONS The Human Reliability Analysis of Cataract Surgery tool is useful for identifying where technical errors occur during phacoemulsification cataract surgery. The study findings, including the high executional error rate, could be used to enhance and structure resident surgical training and future assessment tools. Face, content, and construct validity of the tool were demonstrated.

Motion Analysis as a Tool for the Evaluation of Oculoplastic Surgical Skill: Evaluation of Oculoplastic Surgical Skill

OBJECTIVE To evaluate motion analysis as a discriminator of ophthalmic plastic surgical skill between surgeons of varying experience. METHODS Thirty subjects were divided into 3 groups based on surgical experience: novice (< 5 performed procedures; n = 10), intermediate (5-100 procedures; n = 10), and expert (> 100 procedures; n = 10). Detailed 3-dimensional motion data from surgeons performing 2 oculoplastic surgical tasks on a wet laboratory skills board were obtained using the Qualisys motion capture system. The first task was a deep 3-1-1 suture. The second was skin closure with a continuous suture. The main outcome measures were time, overall path length, and total number of movements. Kruskal-Wallis analysis was performed to evaluate statistical significance. RESULTS Highly significant differences were found during the skin closure task between all groups for mean time (P = .002), overall path length (P = .002), and number of movements (P = .001). For the deep stitch, highly significant differences were also found for time (P < .001), path length (P < .001), and number of movements (P < .001). CONCLUSIONS Motion analysis, using this technology, was able to differentiate between surgeons of varying experience performing oculoplastic tasks, thus demonstrating construct validity. This technique may be useful in the objective quantitative measurement of oculoplastic skill, with potential applications for training and research.

Ophthalmic plastic surgical skills assessment tool.

Purpose: To present a structured tool to assess ophthalmic plastic surgical skill and to determine its face and content validity. Methods: A 1-page structured subjective evaluation form was developed to evaluate a resident’s oculoplastic surgical skill while performing lateral tarsal strip surgery. The tool consisted of generic task components and global indices evaluated using a 5-point Likert scale. A survey was conducted among a panel of highly experienced oculoplastic surgeons to establish face and content validity of the tool. All feedback was considered and, if feasible, was used to amend the tool. Results: There was more than 90% agreement among the highly experienced oculoplastic surgeons regarding the content and weighting of each assessment component. The final format of the tool is divided in 9 task-specific indices, based on the lateral tarsal strip procedure, and 9 global indices which, after assessment, appraisal, and amendment by our expert panel, demonstrates face and content validity. Conclusions: The Ophthalmic Plastic Surgical Skills Assessment Tool is a structured, quantitative instrument designed to aid in the oculoplastic surgical evaluation and training of residents.

Sub-Tenon anaesthesia: reduction in subconjunctival haemorrhage with controlled bipolar conjunctival cautery.

PurposeTo evaluate the effect of controlled conjunctival cautery on the frequency and extent of subconjunctival haemorrhage (SCH) associated with sub-Tenon anaesthetic (STA) injection in patients with various clotting states.MethodsOne hundred forty-four patients suitable for cataract surgery with STA were prospectively divided into four groups: group A (n=36) were on warfarin (INR 1.8–4.2); group B (n=48) on aspirin (75 mg); group C (n=12) on clopidogrel (75 mg); and group D (n=48) on no anticoagulant or antiplatelet agents. All patients had no other known coagulopathy. Each group was randomly divided into two subgroups, one of which received localised bipolar cautery under microscope control to the STA conjunctival entry site before tissue dissection, whereas the other served as a control. χ2 and Fishers exact tests were used to analyse the data with the SPSS package (v11.0).ResultsConjunctival cautery reduced the frequency of SCH from 67 to 6% in group A (P=0.0001); from 37.5 to 4% in group B (P=0.005); from 50 to 0% in group C (P=0.9); and from 17 to 0% in group D (P=0.55). This overall reduction in SCH was highly significant (P<0.0001), especially in groups A and B. No statistically significant reduction in the extent of SCH was found.ConclusionsControlled localised bipolar conjunctival cautery before STA injection may significantly reduce the frequency of SCH, especially in patients on warfarin or aspirin.

Kinematic analysis of surgical dexterity in intraocular surgery.

OBJECTIVE To evaluate the potential of motion analysis as a discriminator of surgical skill during intraocular surgery. METHODS Twenty-four subjects were divided into 3 groups (n = 8 each) based on the number of completed phacoemulsification procedures: novice (n < 10), intermediate (n = 10-150), and expert (n > 150). The Qualisys motion-capture system obtained data from the surgeons performing (1) corneal wound construction (incision), (2) continuous curvilinear capsulorrhexis (CCC), and (3) phacoemulsification lens extraction on artificial eyes. The main outcome measures were time, overall path length, and total number of movements. Statistical significance was set at P < .05. RESULTS For the incision task, significant differences between the levels of experience were found for time (P = .001), number of movements (P = .001), and path length (P = .05). For the CCC task, significant differences were found between groups for time (P = .03) and number of movements (P = .03), but not for path length (P = .08). For the phacoemulsification task, significant differences were found between the 3 groups for time (P = .04), path length (P = .02), and number of movements (P = .04). CONCLUSIONS Motion analysis differentiated between surgeons with varying levels of experience performing phacoemulsification tasks, thus demonstrating construct validity. This technique may be useful in the objective quantitative measurement of microsurgical skill with potential applications for training and research.

The practice of dacryocystorhinostomy (DCR) surgery by ophthalmologists in the United Kingdom (UK).

Purpose: To study the practice of dacryocystorhinostomy (DCR) surgery by ophthalmologists in the United Kingdom (UK) looking at the evaluation techniques used, surgical variations, and follow-up management of DCR cases. Methods: A mail-shot questionnaire was designed and distributed to every UK consultant ophthalmologist on the specialist register held by the Royal College of Ophthalmologists. The questionnaire consisted of eight questions and an image of a typical DCR candidate so respondents could illustrate details of their surgical incision. The data received was entered into a database and analyzed with the SPSS statistical package. The variation in incisions was divided into various sub-types and quantified accordingly. The chi-square test and analysis of variance (ANOVA) were used to calculate significance, which was set at p < 0.05. Results: A response rate of over 75% was achieved amongst the 800 questionnaires dispatched, almost one-third of which perform DCR surgery. Of these, almost 50% were non-lacrimal specialists. The majority never use the endonasal approach, with 59% never performing preoperative nasal endoscopy. Most respondents use a standard incision 10–15 mm long with routine silicone intubation. Lacrimal specialists tended to remove tubes earlier (week 4 to 8) and suture posterior flaps more often than non-specialists. Significant differences in practice were found between lacrimal and non-lacrimal specialists in most parameters, in addition to differences between members and non-members of the National Oculoplastic Surgery Society. Conclusions: A minimum of 200 DCR surgeons are practicing in the UK where almost 50% are non-lacrimal specialists. Marked variations exist in the perioperative DCR practice.

Digital subtraction dacryocystography and syringing in the management of epiphora.

Aim: To compare the diagnostic information provided by digital subtraction dacryocystography (DCG) and syringing of the nasolacrimal system in patients with epiphora. Methods: Twenty-five lacrimal systems of 17 patients, who presented with unilateral or bilateral epiphora and no concurrent ocular or lid abnormality, were prospectively entered into the study. The patients initially underwent syringing by a lacrimal specialist followed by DCG. Results: Anatomical obstructions were detected in 88% of systems with syringing and in 84% with DCG. The anatomical sites of obstruction varied between the two tests in 20% of lacrimal drainage systems. Additional useful information was provided by DCG in 28% of the cases, including identification of multiple sites of obstruction, the presence of dacryoliths, fistulae, and congenital malpositions of the nasolacrimal sac-duct junction. Conclusion: The two investigations were found to have comparable detection rates for anatomical obstructions. Syringing thus appears to be able to detect the problem in the majority of cases but DCG can help delineate unidentified factors of surgical significance in a selected subgroup of patients.

Povidone iodine causes opacification of silicone intraocular lens implants

Purpose:  Four cases of silicone intraocular lens (IOL) opacifications presented at a routine cataract service at a UK district general hospital. A systematic investigation was performed to identify and eliminate the causative factor.

Kinematic Analysis in Oculoplastic Reconstructive Surgery Measuring Manual Control and Fluidity of Movement

OBJECTIVE To evaluate higher-order kinematic analysis, a technique not previously applied to surgical skills assessment, as a tool for elucidating patterns of movement. METHODS An observational cohort study of 27 subjects, divided into 3 equal groups based on surgical experience consisting of novice (performed <5 prior procedures), intermediate (performed 5-100 prior procedures), and expert (performed >100 prior procedures) subjects. The subjects placed a deep 3-1-1 suture onto a shielded hook on a standardized surgical skills practice board. Detailed 3-dimensional motion data were obtained using a motion capture system. Two novel parameters were used to analyze movement patterns: the frequency distribution (cumulative histogram), describing the distribution of movement sizes used, and the probability density function (normalization of frequency distribution data), evaluating the distribution of motion against the magnitude of movement. The α risk for statistical significance was set at .05. RESULTS We found significant differences among the 3 groups for frequency distribution (P = .02; Kruskal-Wallis test) and probability density function (P = .03). CONCLUSIONS These 2 indices, derived from kinematic analysis, appear to distinguish between groups of test subjects with known differences in surgical experience. The evaluation of higher-order motion patterns appears to be of value in the objective evaluation of surgical skills. This method for assessment of manual skills is likely to provide a better guide as to which patterns of movement have the greatest efficiency for specific tasks.

Thiopurine methyltransferase screening before azathioprine therapy.

Azathioprine is used to treat various inflammatory eye conditions such as uveitis and dysthyroid orbitopathy. Despite good overall clinical response rates, particularly when used as steroid sparing agent, adverse effects such as severe myelosuppression can lead to early withdrawal in approximately a quarter of patients.1,2 Thiopurine methyltransferase (TPMT) is a cytosolic enzyme that metabolises azathioprine in vivo. The risk of azathioprine induced myelosuppression may be predicted by detecting patients with intermediate or low TPMT activity. The human TPMT gene exhibits genetic polymorphism that is evident in all populations studied to date.3 Population studies have shown 89% of white people have high TPMT activity, 11% have intermediate, and 0.3% have …