Optimising Radiation Therapy Dose to the Swallowing Organs at Risk: An In Silico Study of feasibility for Patients with Oropharyngeal Tumours.

Recent evidence suggests that reducing radiotherapy dose delivered to specific anatomical swallowing structures [Swallowing Organs at Risk (SWOARs)] may improve swallowing outcomes post-treatment for patients with head and neck cancer. However, for those patients with tumours of the oropharynx, which typically directly overlap the SWOARs, reducing dose to these structures may be unachievable without compromising on the treatment of the disease. To assess the feasibility of dose reduction in this cohort, standard IMRT plans (ST-IMRT) and plans with reduced dose to the SWOARs (SW-IMRT) were generated for 25 oropharyngeal cancer patients (Brouwer et al. in Radiother Oncol 117(1):83-90, https://doi.org/10.1016/j.radonc.2015.07.041 , 2015; Christianen et al. in Radiother Oncol 101(3):394-402, https://doi.org/10.1016/j.radonc.2011.05.015 , 2011). ST-IMRT and SW-IMRT plans were compared for: mean dose to the SWOARs, volume of pharynx and larynx receiving 50 Gy and 60 Gy (V50 and V60 respectively) and overlap between the tumour volume and the SWOARs. Additionally, two different SWOARs delineation guidelines (Brouwer et al. in Radiother Oncol 117(1):83-90, https://doi.org/10.1016/j.radonc.2015.07.041 , 2015; Christianen et al. in Radiother Oncol 101(3):394-402, https://doi.org/10.1016/j.radonc.2011.05.015 , 2011) were used to highlight differences in calculated volumes between existing contouring guidelines. Agreement in SWOARs volumes between the two guidelines was calculated using a concordance index (CI). Despite a large overlap between the tumour and SWOARs, significant (p < 0.05) reductions in mean dose to 4 of the 5 SWOARs, and V50/V60 for the pharynx and larynx were achieved with SW-IMRT plans. Low CIs per structure (0.15-0.45) were found between the two guidelines highlighting issues comparing data between studies when different guidelines have been used (Hawkins et al. in Semin Radiat Oncol 28(1):46-52, https://doi.org/10.1016/j.semradonc.2017.08.002 , 2018; Brodin et al. in Int J Radiat Oncol Biol Phys 100(2):391-407, https://doi.org/10.1016/j.ijrobp.2017.09.041 , 2018). This study found reducing dose to the SWOARs is a feasible practice for patients with oropharyngeal cancer. However, future prospective research is needed to determine if the extent of dose reduction achieved equates to clinical benefits.

Toric implantable collamer lens for patients with moderate to severe myopic astigmatism: 12-month follow-up.

PURPOSE: To report on the 12-month follow-up of 77 eyes with moderate to high myopic astigmatism implanted with toric implantable collamer lenses (ICLs). METHODS: Retrospective case-note review of 77 eyes from 42 patients undergoing toric ICL placement by one surgeon. Preoperative mean spherical equivalent -2.50 dioptres (D) to -15.00 D myopia and 1.00 D to 7.00 D astigmatism. RESULTS: At 12 months, mean manifest refractive cylinder (MRC) decreased 81% from 2.38 D to 0.44 D. MRC within 1.00 D occurred in 99% (76/77) of eyes, whereas 86% (66/77) had MRC within 0.75 D. 99% (76/77) had postoperative best-corrected visual acuity (BCVA) better than or equal to preoperative values, whereas 78% (60/77) gained up to one line BCVA and 1% (1/77) lost one line BCVA. Uncorrected binocular vision of 6/6 or better occurred in 90% (38/42) of patients compared with binocular BCVA of 6/6 or better in 67% (28/42) preoperatively. One ICL was replaced due to low vaulting. Two eyes with astigmatism of 3.25 D and 3.50 D received subsequent laser in situ keratomileusis (LASIK) to reduce residual small refractive errors. Indications for ICL were: myopia too high for LASIK (73%), cornea too thin for LASIK (44%) and contact lens intolerance (33%). Night halos were reported in 10% (8/77) of eyes at 12 months. One ICL was removed due to unrecognized preoperative glaucoma. There were no cases of cataract formation, or endophthalmitis. CONCLUSION: This study is the largest reported series of toric ICL implantation in New Zealand. It supports the safety, efficacy and predictability of toric ICLs to treat myopic astigmatism.

Resurgence of Acanthamoeba keratitis in Auckland, New Zealand: a 7-year review of presentation and outcomes.

PURPOSE: To investigate the presentation, clinical characteristics and outcomes of Acanthamoeba keratitis (AK) in Auckland, New Zealand over a 7-year period. METHODS: Retrospective analysis of all cases of AK treated by the tertiary corneal service at Auckland City Hospital/ University of Auckland Department of Ophthalmology (August 2001 to May 2008). Data were collected regarding age, gender, contact lens history, presenting signs and symptoms, diagnosis at first presentation, time to final diagnosis, identifiable risk factors, presenting and final visual acuity, results of microbiological testing, medical treatment, surgical interventions, recurrence of disease and length of follow up. All photographs and in vivo confocal microscopy images were reviewed. RESULTS: Twenty-five eyes of 25 patients were identified with a diagnosis of AK (mean age 40 +/- 13 years). Ninety-six per cent were contact lens wearers. Mean time to diagnosis was 41 +/- 49 days (range 0-181 days, median 21 days). Fourteen patients (56%) had been treated with topical corticosteroids prior to the diagnosis. Early diagnosis of AK (<21 days) was associated with significantly better final visual acuity and did not require any surgical intervention compared with those diagnosed at a later stage. Six patients, all in the late diagnosis group, required surgical intervention. CONCLUSIONS: AK has become significantly more common in New Zealand in the current decade. This study highlights the fundamental importance of early diagnosis and appropriate management in ensuring favourable outcomes. Practitioners should maintain a clinical suspicion of AK, especially as 96% of the subjects in this study were contact lens wearers.

Spherical implantable collamer lenses for myopia and hyperopia: 126 eyes with 1-year follow up.

BACKGROUND: To report on 1-year follow up of a series of 126 eyes implanted with a spherical implantable collamer lens (ICL). METHODS: Retrospective case note review of 126 eyes (68 patients) undergoing ICL placement by a single surgeon (TG) to correct preoperative mean spherical equivalents between +8.88 and -20.50 D. Main outcome measures included uncorrected visual acuity (UCVA), refraction, best spectacle-corrected VA, unaided binocular vision, adverse events, operative/postoperative complications and patient symptoms. RESULTS: Complete data were available at 1 year on 121 of the 126 eyes (65 out of 68 patients). At 12 months 86% (104/121) had postoperative UCVA better than or equal to preoperative best spectacle-corrected VA, and 98% (118/121) had UCVA within one line of preoperative best spectacle-corrected VA. Ninety-six per cent (116/121) had postoperative UCVA of 6/9 or better, and 100% had postoperative best-corrected visual acuity of 6/12 or better. Ninety-eight per cent (64/65) patients had unaided binocular vision at 1 year of 6/7.5 or better. Average myopia treated was -8.83 D (116 patients), and average hyperopia +7.14 D (10 patients). Two ICLs were replaced because of high vaulting; one eye had increased intraocular pressure that resolved with smaller ICL placement. Four patients had visually insignificant pigment deposits on the ICL at 3/12, but no pigmentary glaucoma. Five patients noticed haloes around lights at night, none preventing driving. CONCLUSIONS: One-year results from this study, the largest reported clinical investigation of the use of ICLs in New Zealand, support the safety, efficacy and predictability of ICL to treat both hyperopic and myopic spherical refractive errors.