Dennis P Han

Medical College of Wisconsin, Milwaukee, Wisconsin, United States

Are you Dennis P Han?

Claim your profile

Publications (88)294.02 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: To compare images of photoreceptor layer disruptions obtained with optical coherence tomography (OCT) and adaptive optics scanning light ophthalmoscopy (AOSLO) in a variety of pathologic states. Five subjects with photoreceptor ellipsoid zone disruption as per OCT and clinical diagnoses of closed-globe blunt ocular trauma (n = 2), macular telangiectasia type 2 (n = 1), blue-cone monochromacy (n = 1), or cone-rod dystrophy (n = 1) were included. Images were acquired within and around photoreceptor lesions using spectral domain OCT, confocal AOSLO, and split-detector AOSLO. There were substantial differences in the extent and appearance of the photoreceptor mosaic as revealed by confocal AOSLO, split-detector AOSLO, and spectral domain OCT en face view of the ellipsoid zone. Clinically available spectral domain OCT, viewed en face or as B-scan, may lead to misinterpretation of photoreceptor anatomy in a variety of diseases and injuries. This was demonstrated using split-detector AOSLO to reveal substantial populations of photoreceptors in areas of no, low, or ambiguous ellipsoid zone reflectivity with en face OCT and confocal AOSLO. Although it is unclear if these photoreceptors are functional, their presence offers hope for therapeutic strategies aimed at preserving or restoring photoreceptor function.
    Retina (Philadelphia, Pa.) 07/2015; DOI:10.1097/IAE.0000000000000618 · 3.24 Impact Factor

  • Jama Ophthalmology 06/2015; 133(8). DOI:10.1001/jamaophthalmol.2015.1485 · 3.32 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Macular hole (MH) and vitreomacular traction (VMT) can involve disruption at the level of the photoreceptor interdigitation zone (IZ) and ellipsoid zone (EZ) with optical coherence tomography (OCT). Confocal adaptive optics scanning light ophthalmoscopy (AOSLO) has been used to examine the photoreceptor mosaic following surgical intervention in patients with MH and VMT, showing large ‘dark areas’ devoid of normal waveguiding cones. Using split-detector AOSLO, which allows visualisation of cone photoreceptor inner segments, we examined the macular cone structure in these disruptions. Methods: Seven eyes from six subjects with MH or VMT were imaged with spectral domain OCT (SD-OCT), confocal AOSLO and non-confocal split-detection AOSLO following pars plana vitrectomy (PPV) for MH or intravitreal injection with ocriplasmin for VMT. Results: Split-detector AOSLO imagery revealed remnant inner segment structure within dark areas observed with confocal AOSLO. In addition, split-detector images demonstrated that not all hyperreflective dots in confocal AOSLO images were derived from cones. Conclusion: Split-detector AOSLO provides additional information for these retinal conditions, and is likely to become an invaluable tool for assessing residual cone structure in conditions where disrupted cone structure interferes with the ability to visualise cells with confocal AOSLO.
    01/2015; 09(01):59. DOI:10.17925/EOR.2015.09.01.59
  • Dennis P Han ·

    Jama Ophthalmology 07/2014; 132(10). DOI:10.1001/jamaophthalmol.2014.1405 · 3.32 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: PurposeTo evaluate sensitivity, specificity and reproducibility of colour difference plot analysis (CDPA) of 103 hexagon multifocal electroretinogram (mfERG) in detecting established hydroxychloroquine (HCQ) retinal toxicity. Methods Twenty-three patients taking HCQ were divided into those with and without retinal toxicity and were compared with a control group without retinal disease and not taking HCQ. CDPA with two masked examiners was performed using age-corrected mfERG responses in the central ring (Rc; 0–5.5 degrees from fixation) and paracentral ring (Rp; 5.5–11 degrees from fixation). An abnormal ring was defined as containing any hexagons with a difference in two or more standard deviations from normal (colour blue or black). ResultsCategorical analysis (ring involvement or not) showed Rc had 83% sensitivity and 93% specificity. Rp had 89% sensitivity and 82% specificity. Requiring abnormal hexagons in both Rc and Rp yielded sensitivity and specificity of 83% and 95%, respectively. If required in only one ring, they were 89% and 80%, respectively. In this population, there was complete agreement in identifying toxicity when comparing CDPA using Rp with ring ratio analysis using R5/R4 P1 ring responses (89% sensitivity and 95% specificity). Continuous analysis of CDPA with receiver operating characteristic analysis showed optimized detection (83% sensitivity and 96% specificity) when ≥4 abnormal hexagons were present anywhere within the Rp ring outline. Intergrader agreement and reproducibility were good. Conclusions Colour difference plot analysis had sensitivity and specificity that approached that of ring ratio analysis of R5/R4 P1 responses. Ease of implementation and reproducibility are notable advantages of CDPA.
    Acta ophthalmologica 02/2014; 92(5). DOI:10.1111/aos.12353 · 2.84 Impact Factor

  • Jama Ophthalmology 11/2013; 132(1). DOI:10.1001/jamaophthalmol.2013.5698 · 3.32 Impact Factor
  • Dennis P Han ·

    Jama Ophthalmology 06/2013; 131(9):1-3. DOI:10.1001/jamaophthalmol.2013.432 · 3.32 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Pediatric cataracts are observed in 1-15 per 10,000 births with 10-25 % of cases attributed to genetic causes; autosomal dominant inheritance is the most commonly observed pattern. Since the specific cataract phenotype is not sufficient to predict which gene is mutated, whole exome sequencing (WES) was utilized to concurrently screen all known cataract genes and to examine novel candidate factors for a disease-causing mutation in probands from 23 pedigrees affected with familial dominant cataract. Review of WES data for 36 known cataract genes identified causative mutations in nine pedigrees (39 %) in CRYAA, CRYBB1, CRYBB3, CRYGC (2), CRYGD, GJA8 (2), and MIP and an additional likely causative mutation in EYA1; the CRYBB3 mutation represents the first dominant allele in this gene and demonstrates incomplete penetrance. Examination of crystallin genes not yet linked to human disease identified a novel cataract gene, CRYBA2, a member of the βγ-crystallin superfamily. The p.(Val50Met) mutation in CRYBA2 cosegregated with disease phenotype in a four-generation pedigree with autosomal dominant congenital cataracts with incomplete penetrance. Expression studies detected cryba2 transcripts during early lens development in zebrafish, supporting its role in congenital disease. Our data highlight the extreme genetic heterogeneity of dominant cataract as the eleven causative/likely causative mutations affected nine different genes, and the majority of mutant alleles were novel. Furthermore, these data suggest that less than half of dominant cataract can be explained by mutations in currently known genes.
    Human Genetics 03/2013; 132(7). DOI:10.1007/s00439-013-1289-0 · 4.82 Impact Factor
  • Dennis P Han · Aniko Szabo ·
    [Show abstract] [Hide abstract]
    ABSTRACT:   Fluoroquinolones are commonly prescribed classes of antibiotics. Despite numerous case reports of ocular toxicity, a pharmacoepidemiological study of their ocular safety, particularly retinal detachment, has not been performed.   To examine the association between use of oral fluoroquinolones and the risk of developing a retinal detachment.   Nested case-control study of a cohort of patients in British Columbia, Canada, who had visited an ophthalmologist between January 2000 and December 2007. Retinal detachment cases were defined as a procedure code for retinal repair surgery within 14 days of a physician service code. Ten controls were selected for each case using risk-set sampling, matching on age and the month and year of cohort entry.   The association between retinal detachment and current, recent, or past use of an oral fluoroquinolone.   From a cohort of 989 591 patients, 4384 cases of retinal detachment and 43 840 controls were identified. Current use of fluoroquinolones was associated with a higher risk of developing a retinal detachment (3.3% of cases vs 0.6% of controls; adjusted rate ratio [ARR], 4.50 [95% CI, 3.56-5.70]). Neither recent use (0.3% of cases vs 0.2% of controls; ARR, 0.92 [95% CI, 0.45-1.87]) nor past use (6.6% of cases vs 6.1% of controls; ARR, 1.03 [95% CI, 0.89-1.19]) was associated with a retinal detachment. The absolute increase in the risk of a retinal detachment was 4 per 10 000 person-years (number needed to harm = 2500 computed for any use of fluoroquinolones). There was no evidence of an association between development of a retinal detachment and β-lactam antibiotics (ARR, 0.74 [95% CI, 0.35-1.57]) or short-acting β-agonists (ARR, 0.95 [95% CI, 0.68-1.33]).   Patients taking oral fluoroquinolones were at a higher risk of developing a retinal detachment compared with nonusers, although the absolute risk for this condition was small.
    Jama Ophthalmology 01/2013; 131(1):91-3. DOI:10.1001/jamaophthalmol.2013.559 · 3.32 Impact Factor
  • Jason A Croskrey · Dennis P Han ·
    [Show abstract] [Hide abstract]
    ABSTRACT: Purpose: To evaluate the rates of adverse reactions to suture materials and compare the rates for plain gut, polyglycolic acid, and polyglactin 910. Methods: Postoperative adverse suture reaction rates were compared using Fisher exact test. One hundred and forty-six patients who underwent pars plana vitrectomy were included in this study. Results: Adverse suture reaction rates were 2% (1/48) for plain gut, 30% (6/20) for polyglycolic acid, and 12% (11/78) for polyglactin 910. Conclusion: Plain gut suture was associated with fewer adverse suture reactions when compared with polyglycolic acid and polyglactin 910 and seems to be suitable for sclerotomy closure.
    Retinal Cases & Brief Reports 01/2013; 7(3):297-9. DOI:10.1097/ICB.0b013e31828ef096
  • [Show abstract] [Hide abstract]
    ABSTRACT: Purpose: To describe the effect of scleral buckle (SB) removal on preoperative symptoms and signs prompting removal and to assess the risk of recurrent retinal detachment (RD) after SB removal. Methods: A retrospective study of 36 patients who underwent SB removal between August 1988 and December 2007 was performed. Indications for SB removal, presence or absence of pain or diplopia, and recurrence of RD were recorded. Composite RD rates were estimated from previously published studies and stratified into those occurring during the previtrectomy era versus later (1980 to present). Results: Mean follow-up time was 75.5 months after SB removal. Thirty-two of 33 patients (97%) who had preoperative pain had symptom relief. Twelve of 12 patients who had clinical infection had resolution. Of the four patients with diplopia, two experienced complete resolution and two reported substantial improvement but required prisms to obtain single vision. Four of 34 patients (12%) whose retinas were attached at the time of SB removal developed recurrent RD but were successfully repaired without significant visual loss from the RD. Conclusion: Scleral buckle removal is effective in eliminating SB-related pain and infection. Symptomatic diplopia can sometimes improve after SB removal. The rates of RD after SB removal observed in this study (12%) and in others performed in the era of vitrectomy were notably lower than those of previous reports.
    Retina (Philadelphia, Pa.) 10/2012; 33(2). DOI:10.1097/IAE.0b013e31826415d9 · 3.24 Impact Factor
  • Dennis P Han · Melody Chin · Kenneth B Simons · Daniel M Albert ·

    Archives of ophthalmology 10/2012; 130(10):1337-9. DOI:10.1001/archophthalmol.2012.2305 · 4.40 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: PURPOSE: To examine retinal structure and changes in photoreceptor intensity after dark adaptation in patients with complete congenital stationary night blindness and Oguchi disease. DESIGN: Prospective, observational case series. METHODS: We recruited 3 patients with complete congenital stationary night blindness caused by mutations in GRM6, 2 brothers with Oguchi disease caused by mutations in GRK1, and 1 normal control. Retinal thickness was measured from optical coherence tomography images. Integrity of the rod and cone mosaic was assessed using adaptive optics scanning light ophthalmoscopy. We imaged 5 of the patients after a period of dark adaptation and examined layer reflectivity on optical coherence tomography in a patient with Oguchi disease under light- and dark-adapted conditions. RESULTS: Retinal thickness was reduced in the parafoveal region in patients with GRM6 mutations as a result of decreased thickness of the inner retinal layers. All patients had normal photoreceptor density at all locations analyzed. On removal from dark adaptation, the intensity of the rods (but not cones) in the patients with Oguchi disease gradually and significantly increased. In 1 Oguchi disease patient, the outer segment layer contrast on optical coherence tomography was 4-fold higher under dark-adapted versus light-adapted conditions. CONCLUSIONS: The selective thinning of the inner retinal layers in patients with GRM6 mutations suggests either reduced bipolar or ganglion cell numbers or altered synaptic structure in the inner retina. Our finding that rods, but not cones, change intensity after dark adaptation suggests that fundus changes in Oguchi disease are the result of changes within the rods as opposed to changes at a different retinal locus.
    American Journal of Ophthalmology 09/2012; 154(6). DOI:10.1016/j.ajo.2012.06.003 · 3.87 Impact Factor
  • Source

    Archives of ophthalmology 04/2012; 130(4):518-21. DOI:10.1001/archophthalmol.2011.2878 · 4.40 Impact Factor
  • Dennis P Han · Dale K Heuer ·

    Archives of ophthalmology 03/2012; 130(3):380-2. DOI:10.1001/archopthalmol.2011.1097 · 4.40 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To evaluate the utility of ring ratios in detecting hydroxychloroquine (HCQ) related retinal toxicity using the 103-hexagon multifocal electroretinogram (mfERG). Retrospective cross-sectional study. 23 patients taking HCQ were consecutively evaluated for retinal toxicity and divided into those without (HCQ-non-toxic group) and with documented visual field loss (HCQ-toxic group). A control patient group without retinal disease and not on HCQ was used for comparison. 103-hexagon P(1) mfERG amplitude response densities were analysed by averaging the 103 responses into six (age-corrected) concentric rings (R(1)-R(6)), calculating standard ring ratios (R(1):R(2)-R(1):R(6)) and R(5) ring ratios (R(5):R(1)-R(5):R(6)). Receiver operating characteristic curves were used to compare these tests for detecting toxicity. Relative to HCQ-non-toxic and control groups, the HCQ-toxic group showed generalised reduction of the 103-hexagon mfERG absolute responses most prominent in the foveal/pericentral regions. R(5) ring ratios were superior to standard ring ratios in discriminating the HCQ-toxic from the HCQ-non-toxic and control groups and were approximately equivalent to pericentral absolute ring responses in detecting HCQ retinal toxicity by receiver operating characteristic criteria, with R(5):R(4) and R(5):R(3) ratios performing best. However, R(5) ring ratios revealed improved sensitivity over absolute ring responses (89% vs 73%) at a 95% specificity threshold. Ring ratio analysis using the R(5) ring response as the 'internal reference ring' appeared equivalent to pericentral absolute ring responses in detecting HCQ retinal toxicity, and possibly superior at clinically desirable specificity thresholds. R(5) ring ratios did not require age correction, a potential clinical advantage over absolute ring responses.
    The British journal of ophthalmology 02/2012; 96(5):723-9. DOI:10.1136/bjophthalmol-2011-300504 · 2.98 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To compare 20-gauge standard pars plana vitrectomy (PPV) with transconjunctival cannulated PPV in the development of intraoperative retinal breaks and postoperative rhegmatogenous retinal detachments (RRDs) in a large series of patients undergoing PPV for macular pucker or macular hole. This study was conducted at an academic tertiary care vitreoretinal practice in Milwaukee, Wisconsin. Patients undergoing 3-port PPV with standard 20-gauge instrumentation were compared with patients undergoing 3-port PPV with transconjunctival cannulated systems, including 20 gauge, 23 gauge, and 25 gauge, from January 1, 2003, through December 31, 2009. The main outcome measures were rates of intraoperative retinal breaks and postoperative RRD. Four hundred twenty-six unique eyes met inclusion criteria. Fifty-four of 426 eyes (12.7%) were diagnosed as having new retinal tears intraoperatively as follows: 47 of 204 patients (23.0%) undergoing the standard 20-gauge procedure developed intraoperative retinal tears compared with 7 of 211 patients (3.3%) undergoing the transconjunctival cannulated procedure (risk ratio [RR], 0.12; 95% CI, 0.05-0.26; P < .001). Patients experiencing intraoperative retinal tears were not at increased risk of developing postoperative RRD (RR, 1.4; 95% CI, 0.39-5.0; P = .61). Although a trend was present, transconjunctival cannulated vitrectomy was not significantly protective against the development of postoperative RRD (RR, 0.60; 95% CI, 0.17-1.3; P = .14). Transconjunctival cannulated PPV, including 20-gauge, 23-gauge, and 25-gauge systems, is associated with significantly reduced rates of intraoperative retinal tear formation compared with standard 20-gauge PPV.
    Archives of ophthalmology 02/2012; 130(2):186-9. DOI:10.1001/archopthalmol.2011.1378 · 4.40 Impact Factor
  • Source
    Dennis P Han · William J O'Brien · Brian Higgins ·
    [Show abstract] [Hide abstract]
    ABSTRACT: Gamunex 10% (Talecris Biotherapeutics, Research Triangle Park, NC), a commercially available preparation of pooled human immunoglobulin G, has been proposed as an antitoxin therapy against bacterial toxins released in infectious endophthalmitis. Its biocompatibility with two commonly used intraocular infusion fluids was evaluated to determine feasibility of its clinical application in endophthalmitis treatment. Gamunex 10% was mixed with BSS or BSS Plus (Alcon Laboratories, Fort Worth, TX) such that it constituted a range of 1.25%-50% by volume. Osmolality, pH, optical density, and ionic strength were measured across this range of concentrations. The amount of pH reduction with increasing concentrations of Gamunex 10% was similar for both BSS and BSS Plus. In BSS Plus, solutions containing up to 20% by volume of Gamunex 10% remained at near-physiologic pH (∼7.0 or above). No physiologically significant changes in osmolality or optical density measurements that would be anticipated to have profound physiological effects were observed at any of the measured concentrations, nor was there visual evidence of tubidity/precipitation. A gradual increase in ionic strength was observed with increasing concentrations of Gamunex 10%. Potentially therapeutic mixtures of Gamunex 10% in 2 commonly used intraocular infusion fluids, BSS and BSS Plus, showed no evidence of bioincompatibility when the solutions were evaluated for changes in osmolality, pH, ionic strength, aggregation, or precipitation.
    Journal of ocular pharmacology and therapeutics: the official journal of the Association for Ocular Pharmacology and Therapeutics 06/2011; 27(4):343-6. DOI:10.1089/jop.2011.0009 · 1.47 Impact Factor
  • Source
    Charles C Wykoff · Harry W Flynn · Dennis P Han ·

    American Journal of Ophthalmology 01/2011; 151(1):4-6. DOI:10.1016/j.ajo.2010.08.044 · 3.87 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To describe spectral-domain optical coherence tomography (SD-OCT) and adaptive optics (AO) imaging in hydroxychloroquine retinal toxicity. Two patients with long-term hydroxychloroquine use, subtle perifoveal ophthalmoscopic pigmentary changes, and bilateral perifoveal defects on automated Humphrey visual field (HVF) 10-2 perimetry were imaged using SD-OCT and AO. SD-OCT images demonstrated loss of photoreceptor inner segment/outer segment (IS/OS) junction and a downward "sink-hole" displacement of inner retinal structures in areas of hydroxychloroquine toxicity corresponding to HVF 10-2 defects and ophthalmoscopic clinical examination findings. SD-OCT irregularities in the IS/OS junction were also seen in areas not detected on HVF 10-2. AO images showed disruption of the cone photoreceptor mosaic in areas corresponding to HVF 10-2 defects and SD-OCT IS/OS junction abnormalities. Additionally, irregularities in the cone photoreceptor density and mosaic were seen in areas with normal HVF 10-2 and SD-OCT findings. SD-OCT and AO detected abnormalities that correlate topographically with visual field loss from hydroxychloroquine toxicity as demonstrated by HVF 10-2 and may be useful in the detection of subclinical abnormalities that precede symptoms or objective visual field loss.
    Transactions of the American Ophthalmological Society 12/2009; 107:28-33.

Publication Stats

2k Citations
294.02 Total Impact Points


  • 1987-2015
    • Medical College of Wisconsin
      • • Department of Ophthalmology
      • • Eye Institute
      Milwaukee, Wisconsin, United States
  • 2000
    • Baylor College of Medicine
      Houston, Texas, United States
  • 1996
    • University of Pittsburgh
      • Graduate School of Public Health
      Pittsburgh, Pennsylvania, United States
  • 1990
    • University of Wisconsin - Milwaukee
      Milwaukee, Wisconsin, United States