Dennis P Han

Medical College of Wisconsin, Milwaukee, Wisconsin, United States

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Publications (62)190.36 Total impact

  • Dennis P Han
    Jama Ophthalmology 07/2014; · 3.83 Impact Factor
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    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; · 2.44 Impact Factor
  • Jama Ophthalmology 11/2013; · 3.83 Impact Factor
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    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; · 4.52 Impact Factor
  • Jason A Croskrey, Dennis P Han
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    ABSTRACT: To evaluate the rates of adverse reactions to suture materials and compare the rates for plain gut, polyglycolic acid, and polyglactin 910.
    Retinal Cases & Brief Reports 01/2013; 7(3):297-9.
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    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; · 2.93 Impact Factor
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    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; · 4.02 Impact Factor
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    Archives of ophthalmology 04/2012; 130(4):518-21. · 3.86 Impact Factor
  • Dennis P Han, Dale K Heuer
    Archives of ophthalmology 03/2012; 130(3):380-2. · 3.86 Impact Factor
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    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. · 2.92 Impact Factor
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    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. · 3.86 Impact Factor
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    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. · 1.46 Impact Factor
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    American Journal of Ophthalmology 01/2011; 151(1):4-6. · 4.02 Impact Factor
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    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.
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    ABSTRACT: To quantify the interpretation of fluorescein angiograms of evolving predominantly classic choroidal neovascularization in age-related macular degeneration. Thirty-six fluorescein angiograms of predominantly classic choroidal neovascularization were used to define 22 fluorescein angiogram pairs. Imaging software was used to measure surface area and greatest linear dimension (GLD). Six retina physicians estimated the change in surface area and GLD for each pair before and after demarcation of the lesions' borders and GLD. For enlarging lesions, the smallest changes consistently detected by physicians were a 5% to 15% increase in surface area and a 5% to 15% increase in GLD; for shrinking lesions, they were a 5% to 15% decrease in surface area and a 5% to 15% decrease in GLD. Linear regression demonstrated moderate correlation between physician and software estimates of surface area and GLD change (r(2) = 0.50 and 0.67, respectively; P < .001), which was higher with lesion demarcation (r(2) = 0.91 and 0.93, respectively; P < .001). Computer-assisted demarcation of lesion surface area and GLD reduced variability in physicians' estimates of choroidal neovascularization size change and improved correlation with software measurements.
    Ophthalmic Surgery Lasers and Imaging 11/2009; 40(6):554-60. · 1.32 Impact Factor
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    ABSTRACT: Pars plana vitrectomy with a 20-gauge transconjunctival cannulated sutureless (TCS) system has the potential of combining the advantages of smaller-gauge vitrectomy systems with the economical advantage of not needing to purchase any additional handheld instruments. However, the sclerotomy size is much larger, and self-sealing sclerotomies may be more difficult to construct. Therefore, we evaluated the need for sclerotomy suturing after performing 20-gauge TCS vitrectomy. A retrospective chart review was performed on the first consecutive 55 eyes of 54 patients who underwent 20-gauge TCS vitrectomy. The main outcome measure was the number of sclerotomies requiring suturing and complications. Of the 164 sclerotomies made, 101 sclerotomies (62%) were not sutured, whereas the remaining 63 sclerotomies (38%) were closed with a single transconjunctival- scleral suture. The reasons for suturing included leakage and gaping at the sclerotomy, conjunctiva not covering the sclerotomy site, and prevention of gas leak. Complications noted include premature dislodging of cannulas, retinal tear, hypotony, hemorrhagic choroidals, subconjunctival gas, and less than full gas fill. Twenty-gauge transconjunctival sutureless vitrectomy is associated with risks similar to other cannulated systems while retaining most of the functionality and handheld instrumentation of the 20-gauge approach. A possibly higher sclerotomy suturing rate relative to smaller-gauge approaches is a disadvantage of this technique.
    Retina (Philadelphia, Pa.) 09/2009; 29(9):1294-8. · 2.93 Impact Factor
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    ABSTRACT: Scleral buckle removal is an uncommon procedure performed for various reasons. Microbiological information on explanted scleral buckles remains limited. The authors identified 37 cases of scleral buckle removal during an 18-year period. Bacterial cultures isolated an organism in 4 of 9 patients (44%) with clinical infection. Organisms identified included methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, Mycobacterium abscessus, and coagulase-negative Staphylococcus species. Bacterial cultures isolated an organism in 3 of 11 patients (27%) without clinical infection. Organisms identified included Nocardia species, Alcaligenes xylosoxidans, and Mycobacterium chelonae. Scleral buckles appearing clinically infected may be associated with more virulent organisms and a greater chance of identifying an organism. Bacterial cultures may be of value for scleral buckles upon removal.
    Ophthalmic Surgery Lasers and Imaging 03/2009; 40(2):201-2. · 1.32 Impact Factor
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    ABSTRACT: To identify preoperative, perioperative, and postoperative risk factors for scleral buckle (SB) removal. A retrospective, consecutive, matched, case-control study. Cases included all patients undergoing SB removal between 1988 and 2007 at a single academic center. Case patients were matched against 4 randomly selected control patients who underwent SB implantation during the same year as the case patients. Odds ratios (ORs) were calculated for each factor investigated. Forty cases of SB removal and 148 matched control cases were identified. Three cases of SB removal were omitted from analysis because of incomplete records. Factors associated with SB removal for any reason, according to univariate analysis, included concurrent globe-penetrating injury at the time of SB placement (OR, 24; 95% confidence interval [CI], 2.9-200), concurrent pars plana vitrectomy (PPV) (OR, 17.3; CI, 4.9-61), diabetes mellitus (DM) (OR, 7.3; CI, 1.8-30), prior long-term topical ocular therapy (OR, 4.3; CI, 1.7-11), and subsequent ocular procedures (OR, 3.4; CI, 1.5-7.5). Factors independently associated with SB removal according to multivariate analysis included concurrent globe-penetrating injury (OR, 27.3; CI, 1.7-426), concurrent PPV (OR, 11.3; CI, 2.9-45), DM (OR, 8.9; CI, 1.3-58), and subsequent ocular procedures (OR, 3.9; CI, 1.4-11). Factors that did not alter SB removal risk included patient age; sex; and type, size, or location of buckling elements used. Awareness of these risk factors may be valuable for the surgical planning of retinal detachment repair in patients at higher risk for subsequent SB removal and for risk stratification subsequent to SB implantation.
    Transactions of the American Ophthalmological Society 02/2008; 106:171-7; discussion 177-8.
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    Craig A Lemley, Dennis P Han
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    ABSTRACT: Pars plana vitrectomy (PPV) in children requires that sclerotomy placement be adjusted for changing dimensions of the ciliary body during ocular development. Experience with an aged-based method for sclerotomy placement is described. Using data from previously reported morphometric studies on ciliary body length by age, an age-based method was used for planning sclerotomy location in children between 1 month and 18 years of age. Sclerotomies were placed 1.5 mm posterior to the limbus in those aged 1 to 6 months, 2.0 mm in those 6 months to 1 year, 2.5 mm in those 1 to 2 years, 3.0 mm in those 2 to 6 years, and 3.5 mm in those 6 to 18 years. Between 1993 and mid-2005, 82 pediatric PPV procedures were performed using this scheme. None of the 82 procedures were complicated by inadvertent lens trauma or retinal perforation during sclerotomy placement. The age-based method for sclerotomy placement may provide a useful guideline for vitrectomy in children with normal ocular growth and development.
    Transactions of the American Ophthalmological Society 02/2007; 105:86-89; discussion 89-91.
  • Manvi Prakash, Dennis P Han
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    ABSTRACT: To report the recurrent bullous retinal detachments as complications of photodynamic therapy (PDT) for idiopathic polypoidal choroidal vasculopathy (IPCV). Interventional case report. A pseudophakic 84-year-old-woman had IPCV and decreased vision. Angiography demonstrated macular leakage. PDT with verteporfin was applied. Two days later, visual acuity decreased from 20/50 to 20/400. Examination revealed extensive inferior subretinal fluid, which mimicked a pseudophakic rhegmatogenous retinal detachment. A scleral buckle was placed; no retinal breaks were identified. Vision and fluid resolved over three weeks. Four months later, examination revealed decreased vision and persistent leakage. Two days after repeat PDT, bullous exudative macular detachment recurred. Detachment resolved over two weeks; visual acuity returned to 20/50. IPCV that is treated with PDT may be complicated by iatrogenic bullous exudative retinal detachments that resemble rhegmatogenous detachments. Modified treatment parameters may reduce the risk of recurrence. The natural history likely includes spontaneous resolution and visual recovery.
    American Journal of Ophthalmology 01/2007; 142(6):1079-81. · 4.02 Impact Factor

Publication Stats

787 Citations
190.36 Total Impact Points


  • 1989–2014
    • Medical College of Wisconsin
      • • Eye Institute
      • • Department of Ophthalmology
      Milwaukee, Wisconsin, United States
  • 2004
    • Texas Eye Institute
      Angleton, Texas, United States
  • 1996–2004
    • Bascom Palmer Eye Institute
      Miami, Florida, United States
  • 1990–1997
    • University of Wisconsin - Milwaukee
      Milwaukee, Wisconsin, United States