Christopher W. Heichel

Lens regeneration using endogenous stem cells with gain of visual function

The repair and regeneration of tissues using endogenous stem cells represents an ultimate goal in regenerative medicine. To our knowledge, human lens regeneration has not yet been demonstrated. Currently, the only treatment for cataracts, the leading cause of blindness worldwide, is to extract the cataractous lens and implant an artificial intraocular lens. However, this procedure poses notable risks of complications. Here we isolate lens epithelial stem/progenitor cells (LECs) in mammals and show that Pax6 and Bmi1 are required for LEC renewal. We design a surgical method of cataract removal that preserves endogenous LECs and achieves functional lens regeneration in rabbits and macaques, as well as in human infants with cataracts. Our method differs conceptually from current practice, as it preserves endogenous LECs and their natural environment maximally, and regenerates lenses with visual function. Our approach demonstrates a novel treatment strategy for cataracts and provides a new paradigm for tissue regeneration using endogenous stem cells.

Morphologic and volumetric studies of the meibomian glands in elderly human eyelids.

Purpose: To study the microscopic structure of postmortem human Meibomian glands (MGs) in the elderly. Methods: Human MG samples from left lower eyelids were obtained at autopsy from 5 men and 4 women with a mean age of 63.1 ± 7.67 years. The tissues were fixed and embedded in paraffin. Serial transverse sections 5 μm thick were stained with hematoxylin and eosin (H&E), van Gieson, and Masson blue stains. Computer-assisted 3-dimensional reconstructions of MGs were performed, and morphologic and volumetric data were analyzed. Results: The average length of human MGs in the nasal, central, and temporal areas was 1.551 ± 0.43, 1.654 ± 0.47, and 1.594 ± 0.57 mm, respectively. The average surface area of the glands in the nasal, central, and temporal areas was 0.029 ± 0.03, 0.033 ± 0.01, and 0.056 ± 0.03 mm2, respectively. The average volume of glands in the nasal, central, and temporal areas was 0.054 ± 00.4, 0.056 ± 0.03, and 0.053 ± 0.03 mm3, respectively. A circular, floral arrangement of acini, surrounding the terminal duct just deep to the skin, is probably responsible for the circular arrangement seen clinically around each healthy orifice. We confirmed that most glands are embedded within a cylindrical, connective tissue matrix. Conclusions: We report the dimensions of normal Meibomian acini in an older population. Some structural features observed may explain normal physiologic landmarks or contribute to glandular pathophysiology.

Epithelial Healing and Visual Outcomes of Patients Using Omega-3 Oral Nutritional Supplements Before and After Photorefractive Keratectomy: A Pilot Study

Purpose: To investigate the effect of omega-3 oral nutritional supplementation on corneal reepithelialization, visual acuity, and tear stability after photorefractive keratectomy (PRK). Methods: This is a prospective, randomized, single-blinded controlled therapeutic trial using omega-3 oral nutritional supplements (TheraTears Nutrition for Dry Eyes; Advanced Vision Research—Akorn, Ann Arbor, MI) conducted at our center. Eighteen healthy patients with refractive error between −1 and −8 diopters were recruited and had bilateral PRK. The treatment group (n = 9 subjects) received omega-3 2 weeks before surgery through 1 month after PRK. The control group (n = 9 subjects) was not given omega-3. Epithelial defects were photographed on postoperative days 0 to 5. Reepithelialization (area in square millimeters) was assessed by fluorescein staining until healing. Tear breakup time (TBUT) and uncorrected distance visual acuity were measured at 1 week, and 1 and 3 months postoperatively. Results: Epithelial defect in the treatment group eyes healed faster compared with that of the controls (P = 0.04). The treatment group eyes healed at an average rate of 1.19% [SD = 0.002; 95% confidence interval (CI), 1.04%–1.34%] per hour, versus 0.83% (SD = 0.0008; 95% CI, 0.77%–0.89%) for controls (Mann–Whitney rank-sum test, P < 0.001). The treatment group eyes maintained a significantly longer TBUT from week 1 through 3 months (mean = 9.52 seconds, SD = 0.81; 95% CI, 8.93–10.10), compared with the controls (mean = 5.52 seconds, SD = 0.81; 95% CI, 4.93–6.10; P < 0.001), and all reached 20/20 vision versus only 4 in the control group 1 month after surgery (P = 0.03). Conclusions: Omega-3 oral nutritional supplements decreased the average time for epithelial healing, and improved TBUT and visual acuity recovery in PRK. These findings suggested that omega-3 oral nutritional supplementation may be a beneficial adjunct therapy for PRK patients.

Intraocular lens calculation adjustment after laser refractive surgery using Scheimpflug imaging.

Purpose To test a new method of intraocular lens (IOL) calculation after corneal refractive surgery using Scheimpflug imaging (Pentacam HR) and partial coherence interferometry (PCI) (IOLMaster) that does not require historical data; that is, the Schuster/Schanzlin‐Thomas‐Purcell (SToP) IOL calculator. Setting Shiley Eye Center, San Diego, California, and Walter Reed National Military Medical Center, Bethesda, Maryland, USA. Design Retrospective data analysis and validation study. Methods Data were retrospectively collected from patient charts including data from Scheimpflug imaging and refractive history. Target refraction was calculated using PCI and the Holladay 1 and SRK/T formulas. Regression analysis was performed to explain the deviation of the target refraction, taking into account the following influencing factors: ratio of posterior‐to‐anterior corneal radius, axial length (AL), and anterior corneal radius. Results The regression analysis study included 61 eyes (39 patients) that had laser in situ keratomileusis (57 eyes) or photorefractive keratectomy (4 eyes) and subsequent cataract. Two factors were found that explained the deviation of the target refraction using the Holladay 1 formula; that is, the ratio of the corneal radii and the AL and the ratio of corneal radii for the SRK/T formula. A new IOL adjustment calculator was derived and validated at a second center using 14 eyes (10 patients). Conclusions The error in IOL calculation for normal eyes after laser refractive treatment was related to the ratio of posterior‐to‐anterior corneal radius. A formula requiring Scheimpflug data and suggested IOL power only yielded an improved postoperative result for patients with previous corneal laser refractive surgery having cataract surgery. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Corrigendum: Lens regeneration using endogenous stem cells with gain of visual function

This corrects the article DOI: 10.1038/nature17181

Large benign de novo conjunctival hemangioma in an 11-year-old boy: case report and literature review

Benign hemangiomas are rare vascular tumors of the conjunctiva that typically present clinically in the first few weeks of life and resolve spontaneously. De novo presentation later in childhood has not been well documented. We present the unusual case of an 11-year-old boy with a rapidly growing benign de novo conjunctival hemangioma that was treated with surgical excision.