Dennis P Han

Medical College of Wisconsin, Milwaukee, Wisconsin, United States

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Publications (92)306.66 Total impact

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    ABSTRACT: Background and objective: To evaluate the safety and efficacy of a blunt sub-Tenon's cannula for local anesthesia before vitreoretinal surgery compared to a sharp retrobulbar needle. Patients and methods: Retrospective, comparative study of all patients undergoing vitreoretinal surgery at the Medical College of Wisconsin between August 2009 and November 2013. Institutional review board approval was obtained. Results: Of 940 surgeries performed with a sub-Tenon's cannula, 99% (938 of 940) were completed. Of the 771 surgeries performed with a sharp retrobulbar needle, 99% (770 of 771) were completed. Factors associated with use of a sharp retrobulbar needle over sub-Tenon's cannula were presence of prior scleral buckle (P < .01) and inclusion of scleral buckle placement in the procedure (P < .01). No case of globe perforation, severe retrobulbar hemorrhage, or severe conjunctival chemosis was observed in either group. Conclusion: Blunt sub-Tenon's cannula appears as effective and safe as a sharp retrobulbar needle for local anesthesia during vitreoretinal surgery. Vitreoretinal surgeons may wish to consider a blunt sub-Tenon's cannula for local surgical anesthesia. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:55-59.].
    No preview · Article · Jan 2016 · Ophthalmic Surgery Lasers and Imaging Retina
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    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.
    No preview · Article · Jul 2015 · Retina (Philadelphia, Pa.)

  • No preview · Article · Jun 2015 · Jama Ophthalmology
  • Christian C Swinney · Dennis P Han · Peter A Karth
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    ABSTRACT: Incontinentia pigmenti (IP) is a rare syndrome with skin lesions, ocular abnormalities in the retina and elsewhere, central nervous system abnormalities, and teeth defects. The authors present an updated review of the literature, highlighting diagnosis, epidemiology, pathophysiology, clinical features, and management of IP. IP is an X-linked dominant syndrome with an incidence of 0.0025%; most patients are female. IP is caused by a mutation in the IKBKG gene, causing a loss of function of NF-κß, leaving cells susceptible to apoptosis from intrinsic factors. The cardinal feature of IP is four stages of skin distinctive lesions. Of those with IP, 36.5% have detectable eye pathology and 60% to 90% of those have retinal issues. Peripheral avascularity and macular occlusive disease commonly occur. The authors performed a comprehensive review of Medline from 1947 to 2014. All papers mentioning IP in ophthalmologic journals were reviewed as well as applicable publications from other medical specialties. [Ophthalmic Surg Lasers Imaging Retina. 2015;46:650-657.]. Copyright 2015, SLACK Incorporated.
    No preview · Article · Jun 2015 · Ophthalmic Surgery Lasers and Imaging Retina
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    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.
    No preview · Article · Jan 2015
  • Dennis P Han

    No preview · Article · Jul 2014 · Jama Ophthalmology
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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.
    No preview · Article · Feb 2014 · Acta ophthalmologica

  • No preview · Article · Nov 2013 · Jama Ophthalmology
  • Dennis P Han

    No preview · Article · Jun 2013 · Jama Ophthalmology
  • Jason A Croskrey · Dennis P Han
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    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.
    No preview · Article · Jun 2013 · Retinal Cases & Brief Reports
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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.
    No preview · Article · Mar 2013 · Human Genetics
  • Dennis P Han · Aniko Szabo
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    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.
    No preview · Article · Jan 2013 · Jama Ophthalmology
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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.
    No preview · Article · Oct 2012 · Retina (Philadelphia, Pa.)

  • No preview · Article · Oct 2012 · Archives of ophthalmology
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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.
    Full-text · Article · Sep 2012 · American Journal of Ophthalmology
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    Full-text · Article · Apr 2012 · Archives of ophthalmology
  • Dennis P Han · Dale K Heuer

    No preview · Article · Mar 2012 · Archives of ophthalmology
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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.
    No preview · Article · Feb 2012 · The British journal of ophthalmology
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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.
    Full-text · Article · Feb 2012 · Archives of ophthalmology
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    Dennis P Han · William J O'Brien · Brian Higgins
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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.
    Preview · Article · Jun 2011 · Journal of ocular pharmacology and therapeutics: the official journal of the Association for Ocular Pharmacology and Therapeutics

Publication Stats

2k Citations
306.66 Total Impact Points

Institutions

  • 1987-2015
    • Medical College of Wisconsin
      • • Department of Ophthalmology
      • • Eye Institute
      Milwaukee, Wisconsin, United States
  • 2005
    • Baylor University
      Waco, Texas, United States
  • 2000
    • Baylor College of Medicine
      Houston, Texas, United States
  • 1996
    • University of Pittsburgh
      • Graduate School of Public Health
      Pittsburgh, Pennsylvania, United States
  • 1992
    • Texas Eye Institute
      انغلتون، تكساس, Texas, United States
  • 1990
    • University of Wisconsin - Milwaukee
      Milwaukee, Wisconsin, United States