Contact lens-related corneal infection in Australia

Microbial keratitis is a rare but potentially severe sight-threatening condition, associated with societal burden, cost and morbidity. Compared with microbial keratitis without lens wear, the disease in contact lens wear is more common, occurs at an earlier age, has lower morbidity and is more often caused by Pseudomonas aeruginosa and Acanthamoeba spp. Resistance to common antibiotics is infrequent in contact lens-related isolates and there is little evidence to suggest increasing bacterial resistance over time. There is some evidence for increased reporting of cases of Acanthamoeba keratitis internationally. The incidence of contact lens-related microbial keratitis has remained stable over time. Rates vary with wear modality, with the lowest risk of severe disease in daily disposable and rigid gas permeable contact lens wear; however, there are limited studies in daily wear silicone hydrogel and in contemporary daily disposable contact lenses. Risk factors for contact lens-related microbial keratitis can be either modifiable or non-modifiable and interventions to reduce the risk of, or severity of disease may be prioritised based on the attributable risk. Key risk factors based on high attributable risk include any overnight wear, failing to wash and dry hands prior to handling lenses and poor storage case hygiene practice. The strong link between microbial keratitis and storage case hygiene and replacement suggests the relevance of microbial contamination of the storage case. Both risk factors and evidence-based strategies for limiting storage case contamination are presented, including storage case cleaning protocols and antimicrobial storage cases; however, it is unclear if such interventions can ultimately limit the rate or severity of microbial keratitis in daily wear. Emerging challenges include understanding and limiting the risk of infection associated with decorative or cosmetic contact lens wear, particularly in Asia, and in understanding the safety of contact lens modalities for myopia control in a paediatric population     

Risk of Metachronous Colon Cancer Following Surgery for Rectal Cancer in Mismatch Repair Gene Mutation Carriers

Background

Despite regular surveillance colonoscopy, the metachronous colorectal cancer risk for mismatch repair (MMR) gene mutation carriers after segmental resection for colon cancer is high and total or subtotal colectomy is the preferred option. However, if the index cancer is in the rectum, management decisions are complicated by considerations of impaired bowel function. We aimed to estimate the risk of metachronous colon cancer for MMR gene mutation carriers who underwent a proctectomy for index rectal cancer.

Methods

This retrospective cohort study comprised 79 carriers of germline mutation in a MMR gene (18 MLH1, 55 MSH2, 4 MSH6, and 2 PMS2) from the Colon Cancer Family Registry who had had a proctectomy for index rectal cancer. Cumulative risks of metachronous colon cancer were calculated using the Kaplan–Meier method.

Results

During median 9 years (range 1–32 years) of observation since the first diagnosis of rectal cancer, 21 carriers (27 %) were diagnosed with metachronous colon cancer (incidence 24.25, 95 % confidence interval [CI] 15.81–37.19 per 1,000 person-years). Cumulative risk of metachronous colon cancer was 19 % (95 % CI 9–31 %) at 10 years, 47 (95 % CI 31–68 %) at 20 years, and 69 % (95 % CI 45–89 %) at 30 years after surgical resection. The frequency of surveillance colonoscopy was 1 colonoscopy per 1.16 years (95 % CI 1.01–1.31 years). The AJCC stages of the metachronous cancers, where available, were 72 % stage I, 22 % stage II, and 6 % stage III.

Conclusions

Given the high metachronous colon cancer risk for MMR gene mutation carriers diagnosed with an index rectal cancer, proctocolectomy may need to be considered.