Cat-PROM5: a brief psychometrically robust self-report questionnaire instrument for cataract surgery

Purpose

To develop a short, psychometrically robust and responsive cataract patient reported outcome measure suitable for use in high-volume surgical environments.

Methods

A prospective study in which participants completed development versions of questionnaires exploring the quality of their eyesight using items harvested from two existing United Kingdom developed parent questionnaires. Participants were 822 patients awaiting cataract surgery recruited from 4 cataract surgical centres based in the UK. Exclusion criteria were other visually significant comorbidities and age <50 years. An iterative multi-stage process of evaluation using Rasch and factor analyses with sequential item reduction was undertaken.

Results

A definitive item set of just five items delivered performance in accordance with the requirements of the Rasch model: no threshold disordering, no misfitting items, Rasch-based reliability 0.90, person separation 2.98, Cronbach’s α 0.89, good targeting of questions to patients with cataract with pre-operative item mean −0.41 logits and absence of significant floor or ceiling effects, minor deviations of item invariance, and confirmed unidimensionality. The test–re-test repeatability intra-class correlation coefficient was 0.89 with excellent responsiveness to surgery, Cohen’s d −1.45 SD. Rasch calibration values are provided for Cat-PROM5 users.

Conclusions

A psychometrically robust and highly responsive five-item cataract surgery patient reported outcome measure has been developed, which is suitable for use in high-volume cataract surgical services.

Cataract surgery patient-reported outcome measures: a head-to-head comparison of the psychometric performance and patient acceptability of the Cat-PROM5 and Catquest-9SF self-report questionnaires

Background Cataract surgery is the most frequently undertaken NHS surgical procedure. Visual acuity (VA) provides a poor indication of visual difficulty in a complex visual world. In the absence of a suitable outcome metric, recent efforts have been directed towards the development of a cataract patient-reported outcome measure (PROM) of sufficient brevity, precision, and responsiveness to be implementable in routine high volume clinical services.

Aim To compare and contrast the two most promising candidate PROMs for routine cataract surgery.

Method The psychometric performance and patient acceptability of the recently UK developed five-item Cat-PROM5 questionnaire was compared with the English translation of the Swedish nine-item Catquest-9SF using Rasch-based performance metrics and qualitative semistructured interviews.

Results Rasch-based performance was assessed in 822 typical NHS cataract surgery patients across four centres in England. Both questionnaires demonstrated good to excellent performance for all metrics assessed, including Person Reliability Indices of 0.90 (Cat-PROM5) and 0.88 (Catquest-9SF), responsiveness to surgery (Cohen’s standardized effect size) of 1.45 SD (Cat-PROM5) and 1.47 SD (Catquest-9SF) and they were highly correlated with each other (R=0.85). Qualitative assessments confirmed that both questionnaires were acceptable to patients, including in the presence of ocular comorbidities. Preferences were expressed for the shorter Cat-PROM5, which allowed patients to map their own issues to the questions as opposed to the more restrictive specific scenarios of Catquest-9SF.

Conclusion The recently UK developed Cat-PROM5 cataract surgery questionnaire is shorter, with performance and patient acceptability at least as good or better than the previous ‘best of class’ Catquest-9SF instrument.

Long-term recovery of the human corneal endothelium after toxic injury by benzalkonium chloride

INTRODUCTION

The inadvertent intra-ocular administration of benzalkonium chloride-preserved hydroxypropyl methylcellulose during cataract surgery at another hospital in 1999 resulted in toxic corneal endothelial injury and profound postoperative corneal oedema as a result of endothelial decompensation. The long-term effect of this adverse event was assessed.

METHODS

All 19 patients were invited to return for examination including corneal endothelial specular microscopy and pachymetry seven years after the incident. Results were compared with data from one year after the incident.

RESULTS

Five patients attended for examination, one had received a penetrating keratoplasty and was, therefore, excluded. Ten patients had died and four had moved out of the region and were unable to attend. All four study patients were pain free and achieved 6/12 or better. Mean central corneal thickness reduced by 13% from 652.6 microm at one year to 563.4 microm. Mean central corneal endothelial cell density (n = 3) increased 28% from 663.7 cells/mm(2) at one year to 835.7 cells/mm(2) (p<0.05).

CONCLUSIONS

After toxic injury, corneal endothelial function may have a remarkable capacity for recovery even after the first postoperative year. The rise in central endothelial cell density may represent cell migration from less affected areas or cellular proliferation. Should this unfortunate event recur, clinicians may expect continued recovery beyond one year.

Imaging of osteo-odonto-keratoprosthesis by electron beam tomography

AIM

To describe the experience of using electron beam tomography (EBT) in imaging of osteo-odonto-keratoprosthesis (OOKP) to identify early bone and dentine loss which may threaten the viability of the eye.

METHODS

Seven patients with an OOKP in one eye underwent EBT. The OOKP lamina dimensions were measured on EBT and compared to the manual measurements at the time of surgery.

RESULTS

There was a high degree of resolution of the OOKP lamina noted with EBT. In particular, it identified three patients with a marked degree of thinning of the lamina edges. Two of these patients had OOKP that were allografts. The mean time from surgery to examination was 3.6 years (range 1.2-5 years) while the mean age of the patients was 56 years (range 31-79 years).

CONCLUSIONS

It is important to monitor regularly the dimensions and stability of the OOKP lamina as it will help detect cases that are at risk of extrusion of the optical cylinder and consequent endophthalmitis. Prophylactic measures can then be taken to prevent such serious complications from occurring. In this series, the authors found EBT to have excellent resolution and speed and they would support regular scanning of the OOKP lamina in all patients.

Clinical outcome following cataract surgery in very elderly patients

PURPOSE

The number of very elderly patients waiting for cataract surgery is predicted to increase. The aim of our study was to determine the clinical outcome following cataract surgery in this age group.

METHODS

In this retrospective study, patients aged 96 years and above, who underwent cataract surgery between June 1993 and January 2001, were identified. Clinical data were retrieved from their medical records. Living patients were further invited for clinical examination.

RESULTS

In all, 34 eyes of 21 patients (20 females) were identified. Six patients were deceased. In total, 30/34 eyes had phacoemulsification and four had extracapsular extraction. Preoperative vision was <or=6/36 in 24/34 eyes (70.59%) and <or=CF in 16/34 eyes (47.06%). Postoperative vision was >or=6/60 in 25/34 eyes (73.53%), >or=6/18 in 21/34 eyes (61.76%), and >or=6/9 in 10/34 eyes (29.41%). Visual acuity improved in 24/34 eyes (70.59%) and remained the same in 6/34 eyes. Complications included anterior capsule tear (three), zonular dialysis with vitreous loss (one), posterior capsule rupture with vitreous loss (one), incarceration of iris to paracentesis wound (two), postoperative uveitis (two), and posterior capsular opacification (19). In all, 7/34 eyes had undergone YAG capsulotomy.

CONCLUSION

Surgeons should not be deterred from offering cataract surgery to the very elderly as successful visual rehabilitation is the norm. A further prospective multicentre study is required to confirm the benefits and assess the risks of cataract surgery in this age group.

A model for the preliminary biological screening of potential keratoprosthetic biomaterials

A series of in vitro screening assays for the preliminary selection of biomaterials for use in the fabrication of artificial corneas (keratoprostheses) (KPros) have been investigated. These screening assays assessed the initial binding of inflammatory and cell adhesive proteins, activation of inflammatory proteins, adhesion of keratocytes, epithelial cells and macrophages and the production of inflammatory cytokines by keratocytes contacting biomaterials. Central optic biomaterials were selected on the basis of low-inflammatory and cell adhesion potential. Peripheral skirt materials were selected on the basis of low-inflammatory potential but good cell adhesion to anchor the implant within the host cornea. Green fluorescent protein (GFP) gene transfer was used in a novel context to investigate cell invasion in the absence of external staining techniques. Confocal laser scanning microscopy and scanning electron microscopy were used to investigate GFP positive keratocyte invasion of porous materials. The results of in vitro assays were compared to a corneal organ culture system in which the biomaterials were assessed within a stromal environment. A range of polyurethane-based interpenetrating polymers with a range of water contents were screened. All materials showed low-inflammatory potential. A reduction in biomaterial water content induced an increase in complement C3 and fibronectin binding and in cell adhesion to materials, whilst differences in co-monomer formulation had little impact. The screening methods used in the current study provide a suitable preliminary assessment regime for the in vitro evaluation of potential KPro materials.

Epithelial transdifferentiation and cataract in the human lens

Anterior subcapsular cataracts cause a serious loss of vision and are normally associated with ocular trauma, inflammation or clinical skin conditions. They appear to be accompanied by epithelial cell growth and transdifferentiation where unscheduled production of a number of proteins, including alpha smooth muscle actin (alpha-sma), occurs. Clinical studies have also revealed an up-regulation of the TGFbeta signalling pathway in such cataracts. The present study, using phase contrast and immunofluorescent techniques, was undertaken to investigate the extent of alpha-sma expression in traumatic cataracts, in capsulorhexis specimens obtained during cataract surgery and in aged human lenses from donor eyes. The donor lenses were also exposed to trauma or TGFbeta in culture to observe their relative contribution to alpha-sma production. Dense anterior subcapsular cataracts were relatively rare (<1%), but all showed a pronounced up-regulation of alpha-sma, which was located both in anterior cells of normal appearance and in nucleated fibroblastic cells lying beneath the anterior epithelium. Surprisingly, more than 50% of capsulorhexis specimens from mature cataracts showed expression of alpha-sma, although to a limited extent. Alpha-sma was not expressed in any of the clear donor lenses and culture for 8 days in EMEM did not induce expression. Interestingly, unlike their young animal counterparts, human lenses failed to show the presence of alpha-sma when exposed to 10 ng ml(-1) TGFbeta. However, after culture, lenses with pre-existing cortical opacities did express alpha-sma, as did clear lenses subjected to injury or trauma. It appears that the greater the stress, the greater is the expression of alpha-sma. Cataract, and especially cortical cataract, should therefore be seen as associated with stress-induced signalling pathways in the lens that lead to the transdifferentiation of the anterior epithelial cells.

Sight and comfort: complex procedures in end-stage Stevens-Johnson syndrome

BACKGROUND

We describe our complex surgical techniques in the management of a patient with end-stage ocular surface disease from Stevens-Johnson syndrome.

METHODS AND RESULTS

Her severe discomfort due to absolute ocular dryness in the right eye was successfully treated with submandibular gland autotransplantation. Impending loss of the left eye due to repeated perforation and infection was prevented with a penetrating corneal graft covered by a new modification of a Cutler-Beard-type full-thickness lower lid skin advancement-flap. Visual rehabilitation was achieved by means of osteo-odonto-keratoprosthesis.

CONCLUSION

The procedures described allow the preservation of eyes doomed for enucleation, relief from severe discomfort and rehabilitation from corneal blindness. Due to their complex nature they require the collaborative subspecialist surgical skills of opthalmologists and maxillofacial surgeons.

Costs and gains of complex procedures to rehabilitate end stage ocular surface disease

BACKGROUND

The management of patients with end stage ocular surface disease sometimes requires extensive surgical treatment that can only be provided by specialised ophthalmology. The authors discuss the costs and gains of such complex techniques based on a case of bilateral corneal blindness secondary to Stevens-Johnson syndrome.

METHODS AND RESULTS

Despite multiple lid surgery for trichiasis and repeated corneal grafting for perforations a white female patient became bilaterally blind at the age of 29 years. She also suffered from disabling discomfort in the right dry eye. At the age of 52 a two stage osteo-odonto-keratoprosthesis achieved visual rehabilitation in the left eye and microvascular transplantation of an autologous, submandibular gland resulted in sufficient lubrication to alleviate her severe discomfort in the right eye. As a result of these procedures she was able to take up a regular job again. The total costs of rehabilitation were pound 13 661 which compare with annual gains and regains for society of pound 13 497. An additional pound 4625 was saved annually in guide dog costs.

CONCLUSION

This estimate shows that despite the expense of these complex techniques gains are made well within the second year after rehabilitation. In view of the benefit in quality of life for the patient and monetary savings for society these procedures should be funded by national health services at specialist centres.