The Lanindar test: a method of evaluating patient suitability for cataract surgery using assisted topical anaesthesia.

AIM: To evaluate an office-based Lanindar (light and nociceptive interaction noting distress and response) test to assist in the assessment of patient suitability for assisted topical anaesthesia (ATA) during phacoemulsification. METHODS: The Lanindar test was carried out at the preoperative assessment of 716 consecutive patients in the office of one of the authors (ICF). A standard desk lamp was shone in each patient's eye after pupillary dilation, while simultaneously elevating the upper eyelid digitally. A negative test indicated patient hypersensitivity to the light and aversion to digital pressure on the upper eyelid. A positive test was indicated by the patient feeling comfort and lack of blepharospasm and withdrawal in response to the light and digital pressure. chi (2) and Fisher's exact tests were used to assess the association between Lanindar results and suitability for ATA. The positive predictive value and specificity of the test as an indicator of patient suitability for ATA were calculated. Visual acuities at 1 and 4 weeks post-operative periods were compared between the ATA and ALA/GA (assisted local anaesthesia/general anaesthesia) group of patients. RESULTS: About 86.7% were Lanindar positive and 98.9% of these patients tolerated ATA. chi (2) and Fisher's exact tests demonstrated a significant association of a positive Lanindar test with successful ATA (chi (2)=660, P<0.001, Fisher's: P<0.001). The positive predictive value and specificity of the test were 98% (95% CI=98.04-99.7%) and 93.14% (95% CI=88.23-98.04%), respectively. Visual acuity outcomes were similar in the ATA and ALA/GA groups. CONCLUSION: The Lanindar is a simple, highly specific, office-based test to determine patient suitability for phacoemulsification under ATA.

Patient perceptions of second eye clear corneal cataract surgery using assisted topical anaesthesia.

AIM: To assess patient recall of intraoperative pain, anxiety, fear, and sensory (visual and auditory) perceptions during second eye clear corneal cataract surgery using assisted topical anaesthesia (ATA), in comparison with first eye cataract surgery using the same technique. METHODS: This prospective, consecutive, observational study was conducted in a free-standing dedicated ophthalmic day surgery centre. A voluntary questionnaire was distributed to 129 consecutive patients who underwent clear corneal cataract surgery using ATA. Two patients had to be converted to block anaesthesia, and were excluded. Patients were asked to rate intraoperative pain, anxiety, and fear using a visual analogue scale (VAS), and recollection of intraoperative visual and auditory perceptions. Results were analysed using the Mann-Whitney U and Spearman correlation tests. RESULTS: There were 70/127 (55%) patients undergoing first eye cataract surgery and 57/127 (45%) undergoing second eye surgery. There was no significant difference in mean pain, anxiety, and fear scores between those undergoing the second eye operation compared with those undergoing their first eye operation. Similarly, there was no significant difference in sensory perceptions between the two cohorts. Overall, there was a small but significant positive correlation between recall of visual and auditory perceptions and combined pain, fear, and anxiety scores (r=0.33, P=0.0002). CONCLUSION: There was no significant difference in levels of intraoperative pain, anxiety, fear, and sensory perceptions experienced by patients between the first eye and second eye surgeries. We recommend that preoperative counselling for a patient's second eye be as comprehensive as for the first eye surgery.

Artist's impression of endocapsular phacoemulsification surgery.

A 77-year-old artist having endocapsular phacoemulsification surgery and intraocular lens implantation illustrated her visual impressions of the procedure in 6 stages, from draping to lens implantation. Her illustrations and commentary indicate that she experienced clear visualization of instruments and colorful abstract imagery. These paintings were shown to 30 consecutive patients to assess their usefulness in preoperatively informing and preparing patients for surgery. With the widespread use of local and topical anesthesia, it is pertinent to the ophthalmic surgeon to understand what patients may seen when vision is retained during the procedure.

Intraoperative complications of 1000 phacoemulsification procedures: a prospective study.

PURPOSE: To determine the frequency and nature of intraoperative complications of endocapsular phacoemulsification cataract surgery. SETTING: Dalcross Private Hospital and the Departments of Ophthalmology, Concord Hospital and Prince of Wales Hospital, Sydney, Australia. METHODS: This prospective study included the first 1000 cases of planned endocapsular phacoemulsification cataract surgery performed by an experienced surgeon. A standardized proforma was completed at the time of surgery. Data recorded included pre-existing ocular abnormalities, duration of surgery, nuclear sclerosis grade, and intraoperative complications. RESULTS: Major complications comprised posterior capsule tears with vitreous loss (1.4%), isolated posterior capsule tears (0.7%), and zonulysis (0.1%). Minor complications included anterior capsule tears (3.8%), iris prolapse (0.6%), and ciliary body incision (0.2%). There was a significant trend toward complications as the nuclear sclerosis grade increased. The incidence of major complications was 9.3% in the first 150 cases and 0.9% in the last 850. This represents a relative risk of 9.9 (95% confidence interval 4.2 to 23.0) of a major complication occurring in the first 150 compared with the later 850 cases. CONCLUSION: The frequency of major and minor complications fell sharply after the first 150 operations and was maintained. This study may provide a guide for beginning phacoemulsification surgeons and a basis for experienced surgeons to compare their performance outcomes.

Phytoestrogens in soy-based infant foods: concentrations, daily intake, and possible biological effects.

Exposure to estrogenic compounds may pose a developmental hazard to infants. Soy products, which contain the phytoestrogens, genistein and daidzein, are becoming increasingly popular as infant foods. To begin to evaluate the potential of the phytoestrogens in these products to affect infants, we measured total genistein and daidzein contents of commercially available soy-based infant formulas, infant cereals, dinners, and rusks. We also assayed phytoestrogens in dairy-based formulas and in breast milk from omnivorous or vegetarian mothers. In most cases, the glucoside forms of the phytoestrogens were hydrolyzed before separation by HPLC. Mean (+/-SEM) total genistein and daidzein contents in four soy infant formulas were 87+/-3 and 49+/-2 microg/g, respectively. The phytoestrogen content of cereals varied with brand, with genistein ranging from 3-287 microg/g and daidzein from 2-276 microg/g. By contrast, no phytoestrogens were detected in dairy-based infant formulas or in human breast milk, irrespective of the mother's diet (detection limit = 0.05 microg/ml). When fed according to the manufacturer's instruction, soy formulas provide the infant with a daily dose rate of total isoflavones (i.e., genistein + daidzein) of approximately 3 mg/kg body weight, which is maintained at a fairly constant level between 0-4 months of age. Supplementing the diet of 4-month-old infants with a single daily serving of cereal can increase their isoflavone intake by over 25%, depending on the brand chosen. This rate of isoflavone intake is much greater than that shown in adult humans to alter reproductive hormones. Since the available evidence suggests that infants can digest and absorb dietary phytoestrogens in active forms and since neonates are generally more susceptible than adults to perturbations of the sex steroid milieu, we suggest that it would be highly desirable to study the effects of soy isoflavones on steroid-dependent developmental processes in human babies.

Effect of insulin-induced hypoglycaemia on secretion patterns and rates of corticotrophin-releasing hormone, arginine vasopressin and adrenocorticotrophin in horses.

To study the effect of hypoglycaemia on secretion rates of corticotrophin-releasing hormone (CRH), arginine vasopressin (AVP) and ACTH in a non-ruminant species, a non-surgical method was used to collect pituitary venous (PitVen) blood every 0.5 or 1 min from seven horses before and after insulin administration (0.4 U/kg i.v.). To assess the effect of PitVen cannulation on results, peripheral hormones were also measured before and after insulin in five horses without PitVen cannulae. Insulin administration lowered plasma glucose in all horses (P < 0.0001; paired t-test). Cortisol concentrations, which were similar in horses with and without PitVen cannulae before insulin, rose significantly after insulin administration in both groups. Most horses showed discomfort as glucose fell. When data from horses with and without PitVen cannulae were pooled, the peak fractional change in cortisol (Spearman's rank correlation coefficient (rs) = -0.94, P < 0.001) and the severity of hypoglycaemic symptoms (rs = -0.61, P < 0.02) were inversely ranked with the glucose nadir. In horses with PitVen cannulae, insulin administration increased secretion rates of ACTH (P < 0.0001), AVP (P < 0.0001) and CRH (P < 0.02). Increments in ACTH (rs = -0.96, P < 0.005) and CRH (rs = -0.81, P < 0.05), but not in AVP, measured during the second half-hour after insulin (i.e. the peak response), were inversely ranked with the glucose nadir. Moreover, ACTH increments were positively ranked with those in CRH (rs = 0.81, P < 0.05), but not in AVP. Nevertheless, in individual horses, minute-to-minute AVP and ACTH concentrations in PitVen blood were always correlated, whereas minute-to-minute CRH and ACTH concentrations were correlated only when glucose dropped below 3.4 mmol/l. In less hypoglycaemic horses, ACTH secretion rose despite little or no change in CRH. We suggest that in horses AVP is the primary acute signal for ACTH release both before and during hypoglycaemia; however, the increasing magnitude of ACTH increments induced by greater degrees of hypoglycaemia is determined largely by selective CRH release, which then augments corticotroph responses to AVP.

Dynamics of the regulation of the hypothalamo-pituitary-adrenal (HPA) axis determined using a nonsurgical method for collecting pituitary venous blood from horses.

Since 1985, we have applied our nonsurgical technique for collecting pituitary venous (PitVen) blood from ambulatory horses to investigate the regulation of adrenocorticotropic hormone (ACTH) secretion. This method offers particular advantages for studying the hypothalamo-pituitary-adrenal axis since its benign nature enables hypothalamic and pituitary interactions to be monitored without disturbing the animal, and the horse's large blood volume allows 3- to 4-ml samples to be collected as frequently as every 20s for prolonged periods so that the secretion patterns of ACTH and its secretagogues can be precisely defined. When PitVen blood was sampled every 20 or 30s during the circadian maximum, arginine vasopressin (AVP) and ACTH secretion patterns were complex and irregular, with mean interpeak intervals of approximately 5 min. Despite their erratic patterns, AVP and ACTH secretions were closely coupled on cross-correlation analysis. By contrast, PitVen corticotropin-releasing hormone (CRH) concentrations were low, relatively stable, and not consistently related to ACTH secretion. However, when cortisol negative feedback was reduced acutely by metyrapone infusion, CRH and AVP secretion were stimulated. Mathematical modeling suggested that CRH had become the more effective secretagogue and that much of the ACTH response was mediated by increased pituitary responsiveness to CRH. Elevated blood osmolality triggered synchronous AVP and ACTH secretion, without altering PitVen CRH. In this case, the source of PitVen AVP was presumably the magnocellular/neurohypophysial pathway, which is thought to respond primarily to changes in blood osmolality and pressure. Our results suggest that this pathway also participates in ACTH regulation. We have studied the effect of several perturbations and found, as have others, that the secretagogues released vary with the stimulus given. For example, vigorous exercise promptly raised PitVen AVP and ACTH, but not PitVen CRH. Hypoglycemia provoked both CRH and AVP secretions, with the CRH increment being inversely proportional to the glucose nadir. Administration of the opioid antagonist, naloxone, increased PitVen ACTH; however, changes in AVP and CRH were variable and overall could not account for the ACTH response. This suggests that endogenous opioids inhibit a third ACTH secretagogue, stimulate an inhibitory factor, or also act at the pituitary. Chronic social stress, induced by confining newcomers with aggressive, resident mares, caused most introduced horses to become submissive. In such horses, plasma cortisol declined to levels similar to those during metyrapone infusion. Despite hypocortisolemia, PitVen ACTH was low, whereas PitVen CRH tended to be elevated. Moreover, chronically stressed horses did not respond to exogenous CRH. We conclude that at rest and during some perturbations AVP is the immediate stimulus for ACTH release. Even ACTH micropulses, previously thought to occur spontaneously, appear to be regulated by AVP in horses. On the other hand, CRH secretion and pituitary responsiveness to CRH rise when cortisol falls, suggesting that a major role for CRH is to fix the cortisol setpoint. However, during chronic stress, these relationships become disturbed, with results to date pointing toward the existence of an ACTH-release inhibiting factor.